Liquid concentrator

ABSTRACT

A liquid concentrator having an evaporator assembly and a cyclonic separator includes features designed to improve the performance of the liquid concentrator. A settling chamber is separated from a sump of the cyclonic separator. A liquid inlet opening into a mixing chamber of the evaporator injects wastewater at low pressures. Features to aid in the cleaning of the liquid concentrator include easy open doors and clean water injection ports for cleaning interior portions of the liquid concentrator.

RELATED APPLICATIONS

This application is a continuation in part of U.S. patent applicationSer. No. 12/846,257, filed on Jul. 29, 2010, which is a continuation inpart of U.S. patent application Ser. No. 12/705,462, filed on Feb. 12,2010, which is a continuation in part of U.S. patent application Ser.No. 12/530,484, filed on Sep. 9, 2009, which is a U.S. national phaseapplication of International (PCT) Patent Application No.PCT/US08/005,672 filed Mar. 12, 2008 and which claims priority benefitof U.S. Provisional Patent Application No. 60/906,743, filed on Mar. 13,2007. This application also claims priority benefit of U.S. ProvisionalPatent Application No. 61/152,248, filed Feb. 12, 2009, and U.S.Provisional Patent Application No. 61/229,650, filed Jul. 29, 2009. Theentire disclosures of each of the applications identified herein arehereby expressly incorporated by reference herein.

FIELD OF THE DISCLOSURE

This application relates generally to liquid concentrators, such aswastewater concentrators, with improved features.

BACKGROUND

Concentration of volatile substances can be an effective form oftreatment or pretreatment for a broad variety of wastewater streams andmay be carried out within various types of commercial processingsystems. At high levels of concentration, many wastewater streams may bereduced to residual material in the form of slurries containing highlevels of dissolved and suspended solids. Such concentrated residual maybe readily solidified by conventional techniques for disposal withinlandfills or, as applicable, delivered to downstream processes forfurther treatment prior to final disposal. Concentrating wastewater cangreatly reduce freight costs and required storage capacity and may bebeneficial in downstream processes where materials are recovered fromthe wastewater.

Characteristics of industrial wastewater streams are very broad as aresult of the large number of industrial processes that produce them. Inaddition to wastewater produced by design under controlled conditionswithin industry, uncontrolled events arising from accidents and naturaldisasters frequently generate wastewater. Techniques for managingwastewater include: direct discharge to sewage treatment plants;pretreatment followed by discharge to sewage treatment plants; on-siteor off-site processes to reclaim valuable constituents; and on-site oroff-site treatment to simply prepare the wastewater for ultimatedisposal. Where the wastewater source is an uncontrolled event,effective containment and recovery techniques must be included with anyof these options.

An important measure of the effectiveness of a wastewater concentrationprocess is the volume of residual produced in proportion to the volumeof wastewater entering the process. In particular, low ratios ofresidual volume to feed volume (high levels of concentration) are themost desirable. Where the wastewater contains dissolved and/or suspendednon-volatile matter, the volume reduction that may be achieved in aparticular concentration process that relies on evaporation of volatilesis, to a great extent, limited by the method chosen to transfer heat tothe process fluid.

Conventional processes that affect concentration by evaporation of waterand other volatile substances may be classified as direct or indirectheat transfer systems depending upon the method employed to transferheat to the liquid undergoing concentration (the process fluid).Indirect heat transfer devices generally include jacketed vessels thatcontain the process fluid, or plate, bayonet tube or coil type heatexchangers that are immersed within the process fluid. Mediums such assteam or hot oil are passed through the jackets or heat exchangers inorder to transfer the heat required for evaporation. Direct heattransfer devices implement processes where the heating medium is broughtinto direct contact with the process fluid, which occurs in, forexample, submerged combustion gas systems.

Indirect heat transfer systems that rely on heat exchangers such asjackets, plates, bayonet tubes or coils are generally limited by thebuildup of deposits of solids on the surfaces of the heat exchangersthat come into direct contact with the process fluid. Also, the designof such systems is complicated by the need for a separate process totransfer heat energy to the heating medium such as a steam boiler ordevices used to heat other heat transfer fluids such as hot oil heaters.This design leads to dependence on two indirect heat transfer systems tosupport the concentration process. Feed streams that produce deposits onheat exchangers while undergoing processing are called fouling fluids.Where feed streams contain certain compounds such as carbonates forwhich solubility decreases with increasing temperature, deposits,generally known as boiler scale, will form even at relatively lowconcentrations due to the elevated temperatures at the surfaces of theheat exchangers. Further, when compounds that have high solubility atelevated temperatures such as sodium chloride are present in thewastewater feed, they will also form deposits by precipitating out ofthe solution as the process fluid reaches high concentrations. Suchdeposits, which necessitate frequent cycles of heat exchange surfacecleaning to maintain process efficiency, may be any combination ofsuspended solids carried into the process with the wastewater feed andsolids that precipitate out of the process fluid. The deleteriouseffects of deposition of solids on heat exchange surfaces limits thelength of time that indirect heat transfer processes may be operatedbefore these processes must be shut down for periodic cleaning. Thesedeleterious effects thereby impose practical limits on the range ofwastewater that might be effectively managed, especially when the rangeof wastewater includes fouling fluids. Therefore, processes that rely onindirect heat transfer mechanisms are generally unsuitable forconcentrating wide varieties of wastewater streams and achieving lowratios of residual to feed volume.

U.S. Pat. No. 5,342,482, which is hereby incorporated by reference,discloses a particular type of direct heat transfer concentrator in theform of a submerged gas process wherein combustion gas is generated anddelivered though an inlet pipe to a dispersal unit submerged within theprocess fluid. The dispersal unit includes a number of spaced-apart gasdelivery pipes extending radially outwardly from the inlet pipe, each ofthe gas delivery pipes having small holes spaced apart at variouslocations on the surface of the gas delivery pipe to disperse thecombustion gas as small bubbles as uniformly as practical across thecross-sectional area of the liquid held within a processing vessel.According to current understanding within the prior art, this designprovides desirable intimate contact between the liquid and the hot gasover a large interfacial surface area. In this process, the intent isthat both heat and mass transfer occur at the dynamic and continuouslyrenewable interfacial surface area formed by the dispersion of a gasphase in a process fluid, and not at solid heat exchange surfaces onwhich deposition of solid particles can occur. Thus, this submerged gasconcentrator process provides a significant advantage over conventionalindirect heat transfer processes. However, the small holes in the gasdelivery pipes that are used to distribute hot gases into the processfluid within the device of U.S. Pat. No. 5,342,482 are subject toblockages by deposits of solids formed from fouling fluids. Thus, theinlet pipe that delivers hot gases to the process fluid is subject tothe buildup of deposits of solids.

Further, as the result of the need to disperse large volumes of gasthroughout a continuous process liquid phase, the containment vesselwithin U.S. Pat. No. 5,342,482 generally requires significantcross-sectional area. The inner surfaces of such containment vessels andany appurtenances installed within them are collectively referred to asthe “wetted surfaces” of the process. These wetted surfaces mustwithstand varying concentrations of hot process fluids while the systemis in operation. For systems designed to treat a broad range ofwastewater streams, the materials of construction for the wettedsurfaces present critical design decisions in relation to both corrosionand temperature resistance which must be balanced against the cost ofequipment and the costs of maintenance/replacement over time. Generallyspeaking, durability and low maintenance/replacement costs for wettedsurfaces are enhanced by selecting either high grades of metal alloys orcertain engineered plastics such as those used in manufacturingfiberglass vessels. However, conventional concentration processes thatemploy either indirect or direct heating systems also require means forhot mediums such as steam, heat transfer oil or gases to transfer heatto the fluid within the vessel. While various different high alloysoffer answers in regard to corrosion and temperature resistance, thecosts of the vessels and the appurtenances fabricated from them aregenerally quite high. Further, while engineered plastics may be usedeither directly to form the containment vessel or as coatings on thewetted surfaces, temperature resistance is generally a limiting factorfor many engineered plastics. For example, the high surface temperaturesof the inlet pipe for hot gas within vessels used in U.S. Pat. No.5,342,482 imposes such limits. Thus, the vessels and other equipmentused for these processes are typically very expensive to manufacture andmaintain.

Moreover, in all of these systems, a source of heat is required toperform the concentration or evaporative processes. Numerous systemshave been developed to use heat generated by various sources, such asheat generated in an engine, in a combustion chamber, in a gascompression process, etc., as a source of heat for wastewaterprocessing. One example of such a system is disclosed in U.S. Pat. No.7,214,290 in which heat is generated by combusting landfill gas within asubmerged combustion gas evaporator, which is used to process leachateat a landfill site. U.S. Pat. No. 7,416,172 discloses a submerged gasevaporator in which waste heat may be provided to an input of the gasevaporator to be used in concentrating or evaporating liquids. Whilewaste heat is generally considered to be a cheap source of energy, to beused effectively in a wastewater processing operation, the waste heatmust in many cases be transported a significant distance from the sourceof the waste heat to a location at which the evaporative orconcentration process is to be performed. For example, in many cases, alandfill operation will have electricity generators which use one ormore internal combustion engines operating with landfill gas as acombustion fuel. The exhaust of these generators or engines, which istypically piped through a muffler and an exhaust stack to the atmosphereat the top of a building containing the electrical generators, is asource of waste heat. However, to collect and use this waste heat,significant amounts of expensive piping and ductwork must be coupled tothe exhaust stack to transfer the waste heat to location of theprocessing system, which will usually be at ground level away from thebuilding containing the generators. Importantly, the piping, ductingmaterials, and control devices (e.g., throttling and shutoff valves)that can withstand the high temperatures (e.g., 950 degrees Fahrenheit)of the exhaust gases within the exhaust stack are very expensive andmust be insulated to retain the heat within the exhaust gases duringtransport. Acceptable insulating materials used for such purposes aregenerally prone to failure due to a variety of characteristics that addcomplexity to the design such as brittleness, tendencies to erode overtime, and sensitivity to thermal cycling. Insulation also increases theweight of the piping, ducting, and control devices, which adds costs tostructural support requirements.

The inventors of the concentrator systems disclosed herein haveattempted to provide evaporator systems with improved features.

SUMMARY

In view of the foregoing, in one aspect a liquid concentrator includesan evaporator assembly arranged to mix wastewater with gas and evaporateliquids from the wastewater, a cyclonic separator arranged to receivethe mixed wastewater and gas from the evaporator assembly and toseparate the gas and the evaporated liquids from solids and thewastewater, a sump disposed below the cyclonic separator arranged tocollect the solids and wastewater separated in the cyclonic separator,and a settling chamber arranged to receive the solids and wastewaterfrom the sump. The settling chamber is separated from the sump.

In another aspect, a liquid concentrator includes an evaporatorassembly, a cyclonic separator, and a door covering an opening into thecyclonic separator, the door attached to the cyclonic separator with ahinge, and a latch for latching the door in a closed position coveringthe opening.

In a further aspect, a liquid concentrator includes an evaporatorassembly defining a mixing corridor having a mixing chamber and anevaporator section connected with the mixing chamber, a cyclonicseparator operatively connected with the evaporator section; and aconduit arranged to transfer wastewater separated in the cyclonicseparator to a liquid inlet opening into the mixing chamber. The liquidinlet has a low-pressure injection port that injects wastewater at apressure of about ten psig or less.

Other aspects and advantages of the invention will become apparent uponreview of the drawings and detailed description provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general schematic diagram of a compact liquid concentrator;

FIG. 2 depicts an embodiment of the liquid concentrator of FIG. 1mounted on a pallet or skid for easy transportation on a truck;

FIG. 3 is a perspective view of a compact liquid concentrator whichimplements the concentration process of FIG. 1, connected to a source ofwaste heat produced by a landfill flare;

FIG. 4 is a perspective view of a heat transfer portion of the compactliquid concentrator of FIG. 3;

FIG. 5 is a front perspective view of an evaporator/concentrator portionof the compact liquid concentrator of FIG. 3;

FIG. 6 is a perspective view of easy opening access doors on a portionof the compact liquid concentrator of FIG. 3;

FIG. 7 is a perspective view of one of the easy opening access doors ofFIG. 6 in the open position;

FIG. 8 is a perspective view of an easy opening latch mechanism used onthe access doors of FIGS. 6 and 7;

FIG. 9 is a schematic diagram of a control system which may be used inthe compact liquid concentrator of FIG. 3 to control the operation ofthe various component parts of the compact liquid concentrator;

FIG. 10 is a diagram of the compact liquid concentrator of FIG. 3attached to a combustion engine stack as a source of waste heat;

FIG. 11 is a general schematic diagram of a second embodiment of acompact liquid concentrator;

FIG. 12 is a top view of the compact liquid concentrator of FIG. 11;

FIG. 13 is a schematic diagram of a third embodiment of a compact liquidconcentrator, the third embodiment being a distributed liquidconcentrator;

FIG. 14 is a side elevational cross-section of the liquid concentratingportion of the distributed liquid concentrator of FIG. 13;

FIG. 15 is a top plan view of the liquid concentrating section of FIG.14;

FIG. 16 is a close up side view of a quencher and venturi section of thedistributed liquid concentrator of FIG. 13;

FIG. 17 is a schematic diagram of a liquid concentrator according toanother aspect;

FIG. 18 is a schematic diagram of a liquid concentrator according to afurther aspect;

FIG. 19 is a schematic diagram of a liquid concentrator according to yetanother aspect; and

FIG. 20 is a schematic diagram of a liquid concentrator according to astill further aspect.

DETAILED DESCRIPTION

FIG. 1 depicts a generalized schematic diagram of a liquid concentrator10 that includes a gas inlet 20, a gas exit 22 and a flow corridor 24connecting the gas inlet 20 to the gas exit 22. The flow corridor 24includes a narrowed portion 26 that accelerates the flow of gas throughthe flow corridor 24 creating turbulent flow within the flow corridor 24at or near this location. The narrowed portion 26 in this embodiment mayformed by a venturi device. A liquid inlet 30 injects a liquid to beconcentrated (via evaporation) into a liquid concentration chamber inthe flow corridor 24 at a point upstream of the narrowed portion 26, andthe injected liquid joins with the gas flow in the flow corridor 24. Theliquid inlet 30 may include one or more replaceable nozzles 31 forspraying the liquid into the flow corridor 24. The inlet 30, whether ornot equipped with a nozzle 31, may introduce the liquid in any directionfrom perpendicular to parallel to the gas flow as the gas moves throughthe flow corridor 24. A baffle 33 may also be located near the liquidinlet 30 such that liquid introduced from the liquid inlet 30 impingeson the baffle and disperses into the flow corridor in small droplets.

As the gas and liquid flow through the narrowed portion 26, the venturiprinciple creates an accelerated and turbulent flow that thoroughlymixes the gas and liquid in the flow corridor 24 at and after thelocation of the inlet 30. This acceleration through the narrowed portion26 creates shearing forces between the gas flow and the liquid droplets,and between the liquid droplets and the walls of the narrowed portion26, resulting in the formation of very fine liquid droplets entrained inthe gas, thus increasing the interfacial surface area between the liquiddroplets and the gas and effecting rapid mass and heat transfer betweenthe gas and the liquid droplets. The liquid exits the narrowed portion26 as very fine droplets regardless of the geometric shape of the liquidflowing into the narrowed portion 26 (e.g., the liquid may flow into thenarrowed portion 26 as a sheet of liquid). As a result of the turbulentmixing and shearing forces, a portion of the liquid rapidly vaporizesand becomes part of the gas stream. As the gas-liquid mixture movesthrough the narrowed portion 26, the direction and/or velocity of thegas/liquid mixture may be changed by an adjustable flow restriction,such as a venturi plate 32, which is generally used to create a largepressure difference in the flow corridor 24 upstream and downstream ofthe venturi plate 32. The venturi plate 32 may be adjustable to controlthe size and/or shape of the narrowed portion 26 and may be manufacturedfrom a corrosion resistant material including a high alloy metal such asthose manufactured under the trade names of Hastelloy®, Inconel® andMonel®.

After leaving the narrowed portion 26, the gas-liquid mixture passesthrough a demister 34 (also referred to as fluid scrubbers orentrainment separators) coupled to the gas exit 22. The demister 34removes entrained liquid droplets from the gas stream. The demister 34includes a gas-flow passage. The removed liquid collects in a liquidcollector or sump 36 in the gas-flow passage, the sump 36 may alsoinclude a reservoir for holding the removed liquid. A pump 40 fluidlycoupled to the sump 36 and/or reservoir moves the liquid through are-circulating circuit 42 back to the liquid inlet 30 and/or flowcorridor 24. In this manner, the liquid may be reduced throughevaporation to a desired concentration. Fresh or new liquid to beconcentrated is input to the re-circulating circuit 42 through a liquidinlet 44. This new liquid may instead be injected directly into the flowcorridor 24 upstream of the venturi plate 32. The rate of fresh liquidinput into the re-circulating circuit 42 may be equal to the rate ofevaporation of the liquid as the gas-liquid mixture flows through theflow corridor 24 plus the rate of liquid extracted through aconcentrated fluid extraction port 46 located in or near the reservoirin the sump 40. The ratio of re-circulated liquid to fresh liquid maygenerally be in the range of approximately 1:1 to approximately 100:1,and is usually in the range of approximately 5:1 to approximately 25:1.For example, if the re-circulating circuit 42 circulates fluid atapproximately 10 gal/min, fresh or new liquid may be introduced at arate of approximately 1 gal/min (i.e., a 10:1 ratio). A portion of theliquid may be drawn off through the extraction port 46 when the liquidin the re-circulating circuit 42 reaches a desired concentration. There-circulating circuit 42 acts as a buffer or shock absorber for theevaporation process ensuring that enough moisture is present in the flowcorridor 24 to prevent the liquid from being completely evaporatedand/or preventing the formation of dry particulate.

After passing through the demister 34 the gas stream passes through aninduction fan 50 that draws the gas through the flow corridor 24 anddemister gas-flow corridor under negative pressure. Of course, theconcentrator 10 could operate under positive pressure produced by ablower (not shown) prior to the liquid inlet 30. Finally, the gas isvented to the atmosphere or directed for further processing through thegas exit 22.

The concentrator 10 may include a pre-treatment system 52 for treatingthe liquid to be concentrated, which may be a wastewater feed. Forexample, an air stripper may be used as a pre-treatment system 52 toremove substances that may produce foul odors or be regulated as airpollutants. In this case, the air stripper may be any conventional typeof air stripper or may be a further concentrator of the type describedherein, which may be used in series as the air stripper. Thepre-treatment system 52 may, if desired, heat the liquid to beconcentrated using any desired heating technique. Additionally, the gasand/or wastewater feed circulating through the concentrator 10 may bepre-heated in a pre-heater 54. Pre-heating may be used to enhance therate of evaporation and thus the rate of concentration of the liquid.The gas and/or wastewater feed may be pre-heated through combustion ofrenewable fuels such as wood chips, bio-gas, methane, or any other typeof renewable fuel or any combination of renewable fuels, fossil fuelsand waste heat. Furthermore, the gas and/or wastewater may be pre-heatedthrough the use of waste heat generated in a landfill flare or stack.Also, waste heat from an engine, such as an internal combustion engine,may be used to pre-heat the gas and/or wastewater feed. Still further,natural gas may be used as a source of waste heat, the natural gas maybe supplied directly from a natural gas well head in an unrefinedcondition either immediately after completion of the natural gas wellbefore the gas flow has stabilized or after the gas flow has stabilizedin a more steady state natural gas well. Optionally, the natural gas maybe refined before being combusted in the flare. Additionally, the gasstreams ejected from the gas exit 22 of the concentrator 10 may betransferred into a flare or other post treatment device 56 which treatsthe gas before releasing the gas to the atmosphere.

The liquid concentrator 10 described herein may be used to concentrate awide variety of wastewater streams, such as waste water from industry,runoff water from natural disasters (floods, hurricanes), refinerycaustic, leachate such as landfill leachate, flowback water fromcompletion of natural gas wells, produced water from operation ofnatural gas wells, etc. The liquid concentrator 10 is practical, energyefficient, reliable, and cost-effective. In order to increase theutility of this liquid concentrator, the liquid concentrator 10 isreadily adaptable to being mounted on a trailer or a moveable skid toeffectively deal with wastewater streams that arise as the result ofaccidents or natural disasters or to routinely treat wastewater that isgenerated at spatially separated or remote sites. The liquidconcentrator 10 described herein has all of these desirablecharacteristics and provides significant advantages over conventionalwastewater concentrators, especially when the goal is to manage a broadvariety of wastewater streams.

Moreover, the concentrator 10 may be largely fabricated from highlycorrosion resistant, yet low cost materials such as fiberglass and/orother engineered plastics. This is due, in part, to the fact that thedisclosed concentrator is designed to operate under minimal differentialpressure. For example, a differential pressure generally in the range ofonly 10 to 30 inches water column is required. Also, because thegas-liquid contact zones of the concentration processes generate highturbulence within narrowed (compact) passages at or directly after theventuri section of the flow path, the overall design is very compact ascompared to conventional concentrators where the gas liquid contactoccurs in large process vessels. As a result, the amount of high alloymetals required for the concentrator 10 is quite minimal. Also, becausethese high alloy parts are small and can be readily replaced in a shortperiod of time with minimal labor, fabrication costs may be cut to aneven higher degree by designing some or all of these parts to be wearitems manufactured from lesser quality alloys that are to be replaced atperiodic intervals. If desired, these lesser quality alloys (e.g.,carbon steel) may be coated with corrosion and/or erosion resistantliners, such as engineered plastics including elastomeric polymers, toextend the useful life of such components. Likewise, the pump 40 may beprovided with corrosion and/or erosion resistant liners to extend thelife of the pump 40, thus further reducing maintenance and replacementcosts.

As will be understood, the liquid concentrator 10 provides directcontact of the liquid to be concentrated and the hot gas, effectinghighly turbulent heat exchange and mass transfer between hot gas and theliquid, e.g., wastewater, undergoing concentration. Moreover, theconcentrator 10 employs highly compact gas-liquid contact zones, makingit minimal in size as compared to known concentrators. The directcontact heat exchange feature promotes high energy efficiency andeliminates the need for solid surface heat exchangers as used inconventional, indirect heat transfer concentrators. Further, the compactgas-liquid contact zone eliminates the bulky process vessels used inboth conventional indirect and direct heat exchange concentrators. Thesefeatures allow the concentrator 10 to be manufactured usingcomparatively low cost fabrication techniques and with reduced weight ascompared to conventional concentrators. Both of these factors favorportability and cost-effectiveness. Thus, the liquid concentrator 10 ismore compact and lighter in weight than conventional concentrators,which make it ideal for use as a portable unit. Additionally, the liquidconcentrator 10 is less prone to fouling and blockages due to the directcontact heat exchange operation and the lack of solid heat exchangersurfaces. The liquid concentrator 10 can also process liquids withsignificant amounts of suspended solids because of the direct contactheat exchange. As a result, high levels of concentration of the processfluids may be achieved without need for frequent cleaning of theconcentrator 10.

More specifically, in liquid concentrators that employ indirect heattransfer, the heat exchangers are prone to fouling and are subject toaccelerated effects of corrosion at the normal operating temperatures ofthe hot heat transfer medium that is circulated within them (steam orother hot fluid). Each of these factors places significant limits on thedurability and/or costs of building conventional indirectly heatedconcentrators, and on how long they may be operated before it isnecessary to shut down and clean or repair the heat exchangers. Byeliminating the bulky process vessels, the weight of the liquidconcentrators and both the initial costs and the replacement costs forhigh alloy components are greatly reduced. Moreover, due to thetemperature difference between the gas and liquid, the relatively smallvolume of liquid contained within the system, the relatively largeinterfacial area between the liquid and the gas, and the reducedrelative humidity of the gas prior to mixing with the liquid, theconcentrator 10 approaches the adiabatic saturation temperature for theparticular gas/liquid mixture, which is typically in the range of about150 degrees Fahrenheit to about 215 degrees Fahrenheit (i.e., thisconcentrator is a “low momentum” concentrator).

Moreover, the concentrator 10 is designed to operate under negativepressure, a feature that greatly enhances the ability to use a verybroad range of fuel or waste heat sources as an energy source to affectevaporation. In fact, due to the draft nature of these systems,pressurized or non-pressurized burners may be used to heat and supplythe gas used in the concentrator 10. Further, the simplicity andreliability of the concentrator 10 is enhanced by the minimal number ofmoving parts and wear parts that are required. In general, only twopumps and a single induced draft fan are required for the concentratorwhen it is configured to operate on waste heat such as stack gases fromengines (e.g., generators or vehicle engines), turbines, industrialprocess stacks, gas compressor systems, and flares, such as landfill gasflares. These features provide significant advantages that reflectfavorably on the versatility and the costs of buying, operating andmaintaining the concentrator 10.

The concentrator 10 may be run in a start up condition, or in a steadystate condition. During the startup condition, the demister 34 sump andre-circulating circuit 42 may be filled with fresh wastewater. Duringinitial processing, the fresh wastewater introduced into the inlet 30 isat least partially evaporated in the narrowed portion 26 and isdeposited in the demister 34 sump in a more concentrated form than thefresh wastewater. Over time, the wastewater in the demister sump 34 andthe re-circulating circuit 42 approaches a desired level ofconcentration. At this point, the concentrator 10 may be run in acontinuous mode where the amount of solids drawn off in the extractionport 46 equals the amount of solids introduced in fresh wastewaterthrough the inlet 30. Likewise, the amount of water evaporated withinthe concentrator 10 is replaced by an equal amount of water in the freshwastewater. Thus, conditions within the concentrator 10 approach theadiabatic saturation point of the mixture of heated gas and wastewater.As a result, the concentrator 10 is highly efficient.

FIG. 2 illustrates a side view of the liquid concentrator 10 mounted ona movable frame 60, such as a pallet, a trailer or a skid. The movableframe is sized and shaped for easy loading on, or connection to, atransportation vehicle 62, such as a tractor-trailer truck. Likewise,such a mounted concentrator may easily be loaded onto a train, a ship oran airplane (not shown) for rapid transportation to remote sites. Theliquid concentrator 10 may operate as a totally self-contained unit byhaving its own burner and fuel supply, or the liquid concentrator 10 mayoperate using an on-site burner and/or an on-site fuel or waste heatsource. Fuels for the concentrator 10 may include renewable fuelsources, such as waste products (paper, wood chips, etc.), and landfillgas. Moreover, the concentrator 10 may operate on any combination oftraditional fossil fuels such as coal or petroleum, renewable fuelsand/or waste heat.

A typical trailer-mounted concentrator 10 may be capable of treating asmuch as one-hundred thousand gallons or more per day of wastewater,while larger, stationary units, such as those installed at landfills,sewage treatment plants, or natural gas or oil fields, may be capable oftreating multiples of one-hundred thousand gallons of wastewater perday.

FIG. 3 illustrates one particular embodiment of a compact liquidconcentrator 110 which operates using the principles described abovewith respect to FIG. 1 and which is connected to a source of waste heatin the form of a landfill flare. Generally speaking, the compact liquidconcentrator 110 of FIG. 3 operates to concentrate wastewater, such aslandfill leachate, using exhaust or waste heat created within a landfillflare which burns landfill gas in a manner that meets the standards setby the U.S. Environmental Protection Agency (EPA) and/or more localregulatory authority. As is known, most landfills include a flare whichis used to burn landfill gas to eliminate methane and other gases priorto release to the atmosphere. Typically, the gas exiting the flare isbetween 1200 and 1500 degrees Fahrenheit and may reach 1800 degreesFahrenheit. The compact liquid concentrator 100 illustrated in FIG. 3 isequally effective in concentrating flowback or produced water fromnatural gas wells and may be operated on exhaust gas from a natural gasflare, or a propane flare, at or near the well head. The natural gasflare may be supplied with natural gas directly from the natural gaswell, in some embodiments.

As illustrated in FIG. 3, the compact liquid concentrator 110 generallyincludes or is connected to a flare assembly 115, and includes a heattransfer assembly 117 (shown in more detail in FIG. 4), an airpre-treatment assembly 119, a concentrator assembly 120 (shown in moredetail in FIG. 5), a fluid scrubber 122, and an exhaust section 124.Importantly, the flare assembly 115 includes a flare 130, which burnslandfill gas (or other combustible fuel) therein according to any knownprinciples, and a flare cap assembly 132. The flare cap assembly 132includes a moveable cap 134 (e.g., a flare cap, an exhaust gas cap,etc.) which covers the top of the flare 130, or other type of stack(e.g., a combustion gas exhaust stack), to seal off the top of the flare130 when the flare cap 134 is in the closed position, or to divert aportion of the flare gas in a partially closed position, and whichallows gas produced within the flare 130 to escape to the atmospherethrough an open end that forms a primary gas outlet 143, when the flarecap 134 is in an open or partially open position. The flare cap assembly132 also includes a cap actuator 135, such as a motor (e.g., an electricmotor, a hydraulic motor, a pneumatic motor, etc., shown in FIG. 4)which moves the flare cap 134 between the fully open and the fullyclosed positions. As shown in FIG. 4, the flare cap actuator 135 may,for example, rotate or move the flare cap 134 around a pivot point 136to open and close the flare cap 134. The flare cap actuator 135 mayutilize a chain drive or any other type of drive mechanism connected tothe flare cap 134 to move the flare cap 134 around the pivot point 136.The flare cap assembly 132 may also include a counter-weight 137disposed on the opposite side of the pivot point 136 from the flare cap134 to balance or offset a portion of the weight of the flare cap 134when moving the flare cap 134 around the pivot point 136. Thecounter-weight 137 enables the actuator 135 to be reduced in size orpower while still being capable of moving or rotating the flare cap 134between an open position, in which the top of the flare 130 (or theprimary combustion gas outlet 143) is open to the atmosphere, and aclosed position, in which the flare cap 134 covers and essentially sealsthe top of the flare 130 (or the primary combustion gas outlet 143). Theflare cap 134 itself may be made of high temperature resistant material,such as stainless steel or carbon steel, and may be lined or insulatedwith refractory material including aluminum oxide and/or zirconium oxideon the bottom portion thereof which comes into direct contact with thehot flare gases when the flare cap 134 is in the closed position.

If desired, the flare 130 may include an adapter section 138 includingthe primary combustion gas outlet 143 and a secondary combustion gasoutlet 141 upstream of the primary combustion gas outlet 143. When theflare cap 130 is in the closed position, combustion gas is divertedthrough the secondary combustion gas outlet 141. The adapter section 138may include a connector section 139 that connects the flare 130 (orexhaust stack) to the heat transfer section 117 using a 90 degree elbowor turn. Other connector arrangements are possible. For example, theflare 130 and heat transfer section 117 may be connected at virtuallyany angle between 0 degrees and 180 degrees. In this case, the flare capassembly 132 is mounted on the top of the adaptor section 138 proximatethe primary combustion gas outlet 143.

As illustrated in FIGS. 3 and 4, the heat transfer assembly 117 includesa transfer pipe 140, which connects to an inlet of the air pre-treatmentassembly 119 to the flare 130 and, more particularly, to the adaptorsection 138 of the flare 130. A support member 142, in the form of avertical bar or pole, supports the heat transfer pipe 140 between theflare 130 and the air pre-treatment assembly 119 at a predeterminedlevel or height above the ground. The heat transfer pipe 140 isconnected to the connector section 139 or the adapter section 138 at thesecondary combustion gas outlet 141, the transfer pipe forming a portionof a fluid passageway between the adapter section 138 and a secondaryprocess, such as a fluid concentrating process. The support member 142is typically necessary because the heat transfer pipe 140 will generallybe made of metal, such as carbon or stainless steel, and may berefractory lined with materials such as aluminum oxide and/or zirconiumoxide, to withstand the temperature of the gas being transferred fromthe flare 130 to the air pre-treatment assembly 119. Thus, the heattransfer pipe 140 will typically be a heavy piece of equipment. However,because the flare 130, on the one hand, and the air pre-treatmentassembly 119 and the concentrator assembly 120, on the other hand, aredisposed immediately adjacent to one another, the heat transfer pipe 140generally only needs to be of a relatively short length, therebyreducing the cost of the materials used in the concentrator 110, as wellas reducing the amount of support structure needed to bear the weight ofthe heavy parts of the concentrator 110 above the ground. As illustratedin FIG. 3, the heat transfer pipe 140 and the air pre-treatment assembly1119 form an upside-down U-shaped structure.

The air pre-treatment assembly 119 includes a vertical piping section150 and an ambient air valve (not shown explicitly in FIGS. 3 and 4)disposed at the top of the vertical piping section 150. The ambient airvalve (also referred to as a damper or bleed valve) forms a fluidpassageway between the heat transfer pipe 140 (or air pre-treatmentassembly 119) and the atmosphere. The ambient air valve operates toallow ambient air to flow through a mesh bird screen 152 (typically wireor metal) and into the interior of the air pre-treatment assembly 119 tomix with the hot gas coming from the flare 130. If desired, the airpre-treatment assembly 119 may include a permanently open sectionproximate to the bleed valve which always allows some amount of bleedair into the air pre-treatment assembly 119, which may be desirable toreduce the size of the required bleed valve and for safety reasons. Apressure blower (not shown) may be connected to the inlet side of theambient air valve, if desired, to force ambient air through the ambientair valve. If a pressure blower is implemented, the bird screen 152 andpermanently open section (if implemented) may be relocated to the inletside of the pressure blower. While the control of the ambient air orbleed valve will be discussed in greater detail hereinafter, this valvegenerally allows the gas from the flare 130 to be cooled to a moredesirable temperature before entering into the concentrator assembly120. The air pre-treatment assembly 119 may be supported in part bycross-members 154 connected to the support member 142. The cross-members154 stabilize the air pre-treatment assembly 119, which is alsotypically made of heavy carbon or stainless steel or other metal, andwhich may be refractory-lined to improve energy efficiency and towithstand the high temperature of the gases within this section of theconcentrator 110. If desired, the vertical piping section 150 may beextendable to adapt to or account for flares of differing heights so asto make the liquid concentrator 110 easily adaptable to many differentflares or to flares of different heights and also to improve efficiencywhen erecting concentrators by correcting for slight vertical and/orhorizontal misalignment of components. This concept is illustrated inmore detail in FIG. 3. As shown in FIG. 3, the vertical piping section150 may include a first section 150A (shown using dotted lines) thatrides inside of a second section 150B thereby allowing the verticalpiping section 150 to be adjustable in length (height).

Generally speaking, the air pre-treatment assembly 119 operates to mixambient air provided through the ambient air valve beneath the screen152 and the hot gas flowing from the flare 130 through the heat transferpipe 140 to create a desired temperature of gas at the inlet of theconcentrator assembly 120.

The liquid concentrator assembly 120 includes a lead-in section 156having a reduced cross-section at the top end thereof which mates thebottom of the piping section 150 to a quencher 159 of the concentratorassembly 120. The concentrator assembly 120 also includes a first fluidinlet 160, which injects new or untreated liquid to be concentrated,such as landfill leachate, into the interior of the quencher 159. Whilenot shown in FIG. 3, the inlet 160 may include a coarse sprayer with alarge nozzle for spraying the untreated liquid into the quencher 159.Because the liquid being sprayed into the quencher 159 at this point inthe system is not yet concentrated, and thus has large amount of watertherein, and because the sprayer is a coarse sprayer, the sprayer nozzleis not subject to fouling or being clogged by the small particles withinthe liquid. As will be understood, the quencher 159 operates to quicklyreduce the temperature of the gas stream (e.g., from about 900 degreesFahrenheit to less than 200 degrees Fahrenheit) while performing a highdegree of evaporation on the liquid injected at the inlet 160. Ifdesired, but not specifically shown in FIG. 3, a temperature sensor maybe located at or near the exit of the piping section 150 or in thequencher 159 and may be used to control the position of the ambient airvalve to thereby control the temperature of the gas present at the inletof the concentrator assembly 120.

As shown in FIGS. 3 and 5, the quencher 159 is connected to liquidinjection chamber which is connected to narrowed portion or venturisection 162 which has a narrowed cross section with respect to thequencher 159 and which has a venturi plate 163 (shown in dotted line)disposed therein. The venturi plate 163 creates a narrow passage throughthe venturi section 162, which creates a large pressure drop between theentrance and the exit of the venturi section 162. This large pressuredrop causes turbulent gas flow and shearing forces within the quencher159 and the top or entrance of the venturi section 162, and causes ahigh rate of gas flow out of the venturi section 162, both of which leadto thorough mixing of the gas and liquid in the venturi section 162. Theposition of the venturi plate 163 may be controlled with a manualcontrol rod 165 (shown in FIG. 5) connected to the pivot point of theplate 163, or via an automatic positioner that may be driven by anelectric motor or pneumatic cylinder (not shown in FIG. 5).

A re-circulating pipe 166 extends around opposite sides of the entranceof the venturi section 162 and operates to inject partially concentrated(i.e., re-circulated) liquid into the venturi section 162 to be furtherconcentrated and/or to prevent the formation of dry particulate withinthe concentrator assembly 120 through multiple fluid entrances locatedon one or more sides of the flow corridor. While not explicitly shown inFIGS. 3 and 5, a number of pipes, such as three pipes of, for example, ½inch diameter, may extend from each of the opposites legs of the pipe166 partially surrounding the venturi section 162, and through the wallsand into the interior of the venturi section 162. Because the liquidbeing ejected into the concentrator 110 at this point is re-circulatedliquid, and is thus either partially concentrated or being maintained ata particular equilibrium concentration and more prone to plug a spraynozzle than the less concentrated liquid injected at the inlet 160, thisliquid may be directly injected without a sprayer so as to preventclogging. However, if desired, a baffle in the form of a flat plate maybe disposed in front of each of the openings of the ½ diameter pipes tocause the liquid being injected at this point in the system to hit thebaffle and disperse into the concentrator assembly 120 as smallerdroplets. In any event, the configuration of this re-circulating systemdistributes or disperses the re-circulating liquid better within the gasstream flowing through the concentrator assembly 120.

The combined hot gas and liquid flows in a turbulent manner through theventuri section 162. As noted above, the venturi section 162, which hasa moveable venturi plate 163 disposed across the width of theconcentrator assembly 120, causes turbulent flow and complete mixture ofthe liquid and gas, causing rapid evaporation of the discontinuousliquid phase into the continuous gas phase. Because the mixing actioncaused by the venturi section 162 provides a high degree of evaporation,the gas cools substantially in the concentrator assembly 120, and exitsthe venturi section 162 into a flooded elbow 164 at high rates of speed.In fact, the temperature of the gas-liquid mixture at this point may beabout 160 degrees Fahrenheit.

As is typical of flooded elbows, a weir arrangement (not shown) withinthe bottom of the flooded elbow 164 maintains a constant level ofpartially or fully concentrated re-circulated liquid disposed therein.Droplets of re-circulated liquid that are entrained in the gas phase asthe gas-liquid mixture exits the venturi section 162 at high rates ofspeed are thrown outward onto the surface of the re-circulated liquidheld within the bottom of the flooded elbow 164 by centrifugal forcegenerated when the gas-liquid mixture is forced to turn 90 degrees toflow into the fluid scrubber 122. Significant numbers of liquid dropletsentrained within the gas phase that impinge on the surface of there-circulated liquid held in the bottom of the flooded elbow 164coalesce and join with the re-circulated liquid thereby increasing thevolume of re-circulated liquid in the bottom of the flooded elbow 164causing an equal amount of the re-circulated liquid to overflow the weirarrangement and flow by gravity into the sump 172 at the bottom of thefluid scrubber 122. Thus, interaction of the gas-liquid stream with theliquid within the flooded elbow 164 removes liquid droplets from thegas-liquid stream, and also prevents suspended particles within thegas-liquid stream from hitting the bottom of the flooded elbow 164 athigh velocities, thereby preventing erosion of the metal that forms theportions of side walls located beneath the level of the weir arrangementand the bottom of the flooded elbow 164.

After leaving the flooded elbow 164, the gas-liquid stream in whichevaporated liquid and some liquid and other particles still exist, flowsthrough the fluid scrubber 122 which is, in this case, a cross-flowfluid scrubber. The fluid scrubber 122 includes various screens orfilters which serve to remove entrained liquids and other particles fromthe gas-liquid stream. In one particular example, the cross flowscrubber 122 may include an initial coarse impingement baffle 169 at theinput thereof, which is designed to remove liquid droplets in the rangeof 50 to 100 microns in size or higher. Thereafter, two removablefilters in the form of chevrons 170 are disposed across the fluid paththrough the fluid scrubber 122, and the chevrons 170 may beprogressively sized or configured to remove liquid droplets of smallerand smaller sizes, such as 20-30 microns and less than 10 microns. Ofcourse, more or fewer filters or chevrons could be used.

As is typical in cross flow scrubbers, liquid captured by the filters169 and 170 and the overflow weir arrangement within the bottom of theflooded elbow 164 drain by gravity into a reservoir or sump 172 locatedat the bottom of the fluid scrubber 122. The sump 172, which may hold,for example approximately 200 gallons of liquid, thereby collectsconcentrated fluid containing dissolved and suspended solids removedfrom the gas-liquid stream and operates as a reservoir for a source ofre-circulating concentrated liquid back to the concentrator assembly 120to be further treated and/or to prevent the formation of dry particulatewithin the concentrator assembly 120 in the manner described above withrespect to FIG. 1. In one embodiment, the sump 172 may include a slopedV-shaped bottom 171 having a V-shaped groove 175 extending from the backof the fluid scrubber 122 (furthest away from the flooded elbow 164) tothe front of the fluid scrubber 122 (closest to the flooded elbow 164),wherein the V-shaped groove 175 is sloped such that the bottom of theV-shaped groove 175 is lower at the end of the fluid scrubber 122nearest the flooded elbow 164 than at an end farther away from theflooded elbow 164. In other words, the V-shaped bottom 171 may be slopedwith the lowest point of the V-shaped bottom 171 proximate the exit port173 and/or the pump 182. Additionally, a washing circuit 177 (FIG. 9)may pump concentrated fluid from the sump 172 to a sprayer 179 withinthe cross flow scrubber 122, the sprayer 179 being aimed to spray liquidat the V-shaped bottom 171. Alternatively, the sprayer 179 may sprayun-concentrated liquid or clean water at the V-shaped bottom 171. Thesprayer 179 may periodically or constantly spray liquid onto the surfaceof the V-shaped bottom 171 to wash solids and prevent solid buildup onthe V-shaped bottom 171 or at the exit port 173 and/or the pump 182. Asa result of this V-shaped sloped bottom 171 and washing circuit 177,liquid collecting in the sump 172 is continuously agitated and renewed,thereby maintaining a relatively constant consistency and maintainingsolids in suspension. If desired, the spraying circuit 177 may be aseparate circuit using a separate pump with, for example, an inletinside of the sump 172, or may use a pump 182 associated with aconcentrated liquid re-circulating circuit described below to sprayconcentrated fluid from the sump 172 onto the V-shaped bottom 171.

As illustrated in FIG. 3, a return line 180, as well as a pump 182,operate to re-circulate fluid removed from the gas-liquid stream fromthe sump 172 back to the concentrator 120 and thereby complete a fluidor liquid re-circulating circuit. Likewise, a pump 184 may be providedwithin an input line 186 to pump new or untreated liquid, such aslandfill leachate, to the input 160 of the concentrator assembly 120.Also, one or more sprayers 185 may be disposed inside the fluid scrubber122 adjacent the chevrons 170 and may be operated periodically to sprayclean water or a portion of the wastewater feed on the chevrons 170 tokeep them clean.

Concentrated liquid also may be removed from the bottom of the fluidscrubber 122 via the exit port 173 and may be further processed ordisposed of in any suitable manner in a secondary re-circulating circuit181. In particular, the concentrated liquid removed by the exit port 173contains a certain amount of suspended solids, which preferably may beseparated from the liquid portion of the concentrated liquid and removedfrom the system using the secondary re-circulating circuit 181. Forexample, concentrated liquid removed from the exit port 173 may betransported through the secondary re-circulating circuit 181 to one ormore solid/liquid separating devices 183, such as settling tanks,vibrating screens, rotary vacuum filters, horizontal belt vacuumfilters, belt presses, filter presses, and/or hydro-cyclones. After thesuspended solids and liquid portion of the concentrated wastewater areseparated by the solid/liquid separating device 183, the liquid portionof the concentrated wastewater with suspended particles substantiallyremoved may be returned to the sump 172 for further processing in thefirst or primary re-circulating circuit connected to the concentrator.

The gas, which flows through and out of the fluid scrubber 122 with theliquid and suspended solids removed therefrom, exits out of piping orductwork at the back of the fluid scrubber 122 (downstream of thechevrons 170) and flows through an induced draft fan 190 of the exhaustassembly 124, from where it is exhausted to the atmosphere in the formof the cooled hot inlet gas mixed with the evaporated water vapor. Ofcourse, an induced draft fan motor 192 is connected to and operates thefan 190 to create negative pressure within the fluid scrubber 122 so asto ultimately draw gas from the flare 130 through the transfer pipe 140,the air pre-treatment assembly 119 and the concentrator assembly 120. Asdescribed above with respect to FIG. 1, the induced draft fan 190 needsonly to provide a slight negative pressure within the fluid scrubber 122to assure proper operation of the concentrator 110.

While the speed of the induced draft fan 190 can be varied by a devicesuch as a variable frequency drive operated to create varying levels ofnegative pressure within the fluid scrubber 122 and thus can usually beoperated within a range of gas flow capacity to assure complete gas flowfrom the flare 130, if the gas being produced by the flare 130 is not ofsufficient quantity, the operation of the induced draft fan 190 cannotnecessarily be adjusted to assure a proper pressure drop across thefluid scrubber 122 itself. That is, to operate efficiently and properly,the gas flowing through the fluid scrubber 122 must be at a sufficient(minimal) flow rate at the input of the fluid scrubber 122. Typicallythis requirement is controlled by keeping at least a preset minimalpressure drop across the fluid scrubber 122. However, if the flare 130is not producing at least a minimal level of gas, increasing the speedof the induced draft fan 190 will not be able to create the requiredpressure drop across the fluid scrubber 122.

To compensate for this situation, the cross flow scrubber 122 isdesigned to include a gas re-circulating circuit which can be used toassure that enough gas is present at the input of the fluid scrubber 122to enable the system to acquire the needed pressure drop across thefluid scrubber 122. In particular, the gas re-circulating circuitincludes a gas return line or return duct 196 which connects the highpressure side of the exhaust assembly 124 (e.g., downstream of theinduced draft fan 190) to the input of the fluid scrubber 122 (e.g., agas input of the fluid scrubber 122) and a baffle or control mechanism198 disposed in the return duct 196 which operates to open and close thereturn duct 196 to thereby fluidly connect the high pressure side of theexhaust assembly 124 to the input of the fluid scrubber 122. Duringoperation, when the gas entering into the fluid scrubber 122 is not ofsufficient quantity to obtain the minimal required pressure drop acrossthe fluid scrubber 122, the baffle 198 (which may be, for example, a gasvalve, a damper such as a louvered damper, etc.) is opened to direct gasfrom the high pressure side of the exhaust assembly 124 (i.e., gas thathas traveled through the induced draft fan 190) back to the input of thefluid scrubber 122. This operation thereby provides a sufficientquantity of gas at the input of the fluid scrubber 122 to enable theoperation of the induced draft fan 190 to acquire the minimal requiredpressure drop across the fluid scrubber 122.

FIG. 6 illustrates the particular advantageous feature of the compactliquid concentrator 110 of FIG. 3 in the form of a set of easy openingaccess doors 200 which may be used to access the inside of theconcentrator 110 for cleaning and viewing purposes. While FIG. 6illustrates easy opening access doors 200 on one side of the fluidscrubber 122, a similar set of doors may be provided on the other sideof the fluid scrubber 122, and a similar door is provided on the frontof the flooded elbow 164, as shown in FIG. 5. As illustrated in FIG. 6,each of the easy access doors 200 on the fluid scrubber 122 includes adoor plate 202, which may be a flat piece of metal, connected to thefluid scrubber 122 via two hinges 204, with the door plate 202 beingpivotable on the hinges 204 to open and close. A plurality ofquick-release latches with pivoting handles 206 are disposed around theperiphery of the door plate 202 and operate to hold the door plate 202in the closed position and so to hold the door 200 shut when the fluidscrubber 122 is operating. In the embodiment shown in FIG. 6, eightquick-release latches 206 are disposed around each of the door plates202, although any other desired number of such quick-release latches 206could be used instead.

FIG. 7 illustrates one of the doors 200 disposed in the open position.As will be seen, a door seat 208 is mounted away from the wall of thefluid scrubber 122 with extension members 209 disposed between the doorseat 208 and the outer wall of the fluid scrubber 122. A gasket 210,which may be made of rubber or other compressible material, is disposedaround the circumference of the opening on the door seat 208. A similargasket may additionally or alternatively be disposed around the outercircumference of inner side of the door plate 202, which provides forbetter sealing when the door 200 is in the closed position.

Each quick-release latch 206, one of which is shown in more detail inFIG. 8, includes a handle 212 and a latch 214 (in this case a U-shapedpiece of metal) mounted on a pivot bar 216 disposed through the handle212. The handle 212 is mounted on a further pivot point member 218 whichis mounted on the outer wall of the door plate 202 via an attachmentbracket 219. The operation of the handle 212 up and around the furtherpivot member 218 (from the position shown in FIG. 8) moves the latch 214towards the outer wall of the fluid scrubber 112 (when the door plate202 is in the closed position) so that the latch 214 may be disposed onthe side of a hook 220 away from the door plate 202, the hook 220 beingmounted on the extension member 209. Rotation of the handle 210 back inthe opposite direction pulls the latch 214 up tight against the hook220, pulling the further pivot member 218 and therefore the door plate202 against the door seat 208. Operation of all of the quick-releaselatches 206 secures the door plate 202 against door seat 208 and thegasket 210 provides for a fluidly secure connection. Thus, closing alleight of the quick-release latches 206 on a particular door 200, asillustrated in FIG. 6, provides a secure and tight-fitting mechanism forholding the door 200 closed.

The use of the easy opening doors 200 replaces the use of a plate withholes, wherein numerous bolts extending from the outer wall of theconcentrator are fitted through the holes on the plate and wherein it isnecessary to tighten nuts on the bolts to draw the plate against thewall of the concentrator. While such a nut and bolt type of securingmechanism, which is typically used in fluid concentrators to allowaccess to the interior of the concentrator, is very secure, operation ofthis configuration takes a long time and a lot of effort when opening orclosing an access panel. The use of the quick opening doors 200 with thequick-release latches 206 of FIG. 6 may be used in this instance becausethe interior of the fluid scrubber 122 is under negative pressure, inwhich the pressure inside the fluid scrubber 122 is less than theambient air pressure, and so does not need the security of a cumbersomebolt and nut type of access panel. Of course, as will be understood, theconfiguration of the doors 200 allows the doors 200 to be easily openedand closed, with only minimal manual effort, and no tools, therebyallowing for fast and easy access to the structure inside of the fluidscrubber 122, such as the impingement baffle 169 or the removablefilters 170, or other parts of the concentrator 110 on which an accessdoor 200 is disposed.

Referring back to FIG. 5, it will be seen that the front the floodedelbow 164 of the concentrator assembly 120 also includes a quick openingaccess door 200, which allows easy access to the inside of the floodedelbow 164. However, similar quick opening access doors could be locatedon any desired part of the fluid concentrator 110, as most of theelements of the concentrator 10 operate under negative pressure.

The combination of features illustrated in FIGS. 3-8 makes for a compactfluid concentrator 110 that uses waste heat in the form of gas resultingfrom the operation of a landfill flare burning landfill gas, which wasteheat would otherwise be vented directly to the atmosphere. Importantly,the concentrator 110 uses only a minimal amount of expensive hightemperature resistant material to provide the piping and structuralequipment required to use the high temperature gases exiting from theflare 130. For example, the small length of the transfer pipe 140, whichis made of the most expensive materials, is minimized, thereby reducingthe cost and weight of the fluid concentrator 110. Moreover, because ofthe small size of the heat transfer pipe 140, only a single supportmember 142 is needed thereby further reducing the costs of building theconcentrator 110. Still further, the fact that the air pre-treatmentassembly 119 is disposed directly on top of the fluid concentratorassembly 120, with the gas in these sections flowing downward towardsthe ground, enables these sections of the concentrator 110 to besupported directly by the ground or by a skid on which these members aremounted. Still further, this configuration keeps the concentrator 110disposed very close to the flare 130, making it more compact. Likewise,this configuration keeps the high temperature sections of theconcentrator 110 (e.g., the top of the flare 130, the heat transfer pipe140 and the air pre-treatment assembly 119) above the ground and awayfrom accidental human contact, leading to a safer configuration. Infact, due to the rapid cooling that takes place in the venturi section162 of the concentrator assembly 120, the venturi section 162, theflooded elbow 164 and the fluid scrubber 122 are typically cool enoughto touch without harm (even when the gases exiting the flare 130 are at1800 degrees Fahrenheit). Rapid cooling of the gas-liquid mixture allowsthe use of generally lower cost materials that are easier to fabricateand that are corrosion resistant. Moreover, parts downstream of theflooded elbow 164, such as the fluid scrubber 122, induced draft fan190, and exhaust section 124 may be fabricated from materials such asfiberglass.

The fluid concentrator 110 is also a very fast-acting concentrator.Because the concentrator 110 is a direct contact type of concentrator,it is not subject to deposit buildup, clogging and fouling to the sameextent as most other concentrators. Still further, the ability tocontrol the flare cap 134 to open and close, depending on whether theconcentrator 110 is being used or operated, allows the flare 130 to beused to burn landfill gas without interruption when starting andstopping the concentrator 110. More particularly, the flare cap 134 canbe quickly opened at any time to allow the flare 130 to simply burnlandfill gas as normal while the concentrator 110 is shut down. On theother hand, the flare cap 134 can be quickly closed when theconcentrator 110 is started up, thereby diverting hot gasses created inthe flare 130 to the concentrator 110, and allowing the concentrator 110to operate without interrupting the operation of the flare 130. Ineither case, the concentrator 110 can be started and stopped based onthe operation of the flare cap 134 without interrupting the operation ofthe flare 130.

If desired, the flare cap 134 may be opened to a partial amount duringoperation of the concentrator 110 to control the amount of gas that istransferred from the flare 130 to the concentrator 110. This operation,in conjunction with the operation of the ambient air valve, may beuseful in controlling the temperature of the gas at the entrance of theventuri section 162.

Moreover, due to the compact configuration of the air pre-treatmentassembly 119, the concentrator assembly 120 and the fluid scrubber 122,parts of the concentrator assembly 120, the fluid scrubber 122, thedraft fan 190 and at least a lower portion of the exhaust section 124can be permanently mounted on (connected to and supported by) a skid orplate 230, as illustrated in FIG. 2. The upper parts of the concentratorassembly 120, the air pre-treatment assembly 119 and the heat transferpipe 140, as well as a top portion of the exhaust stack, may be removedand stored on the skid or plate 230 for transport, or may be transportedin a separate truck. Because of the manner in which the lower portionsof the concentrator 110 can be mounted to a skid or plate, theconcentrator 110 is easy to move and install. In particular, during setup of the concentrator 110, the skid 230, with the fluid scrubber 122,the flooded elbow 164 and the draft fan 190 mounted thereon, may beoffloaded at the site at which the concentrator 110 is to be used bysimply offloading the skid 230 onto the ground or other containment areaat which the concentrator 110 is to be assembled. Thereafter, theventuri section 162, the quencher 159, and the air pre-treatmentassembly 119 may be placed on top of and attached to the flooded elbow164. The piping section 150 may then be extended in height to match theheight of the flare 130 to which the concentrator 110 is to beconnected. In some cases, this may first require mounting the flare capassembly 132 onto a pre-existing flare 130. Thereafter, the heattransfer pipe 140 may be raised to the proper height and attachedbetween the flare 130 and the air pre-treatment assembly 119, while thesupport member 142 is disposed in place. For concentrators in the rangeof 10,000 to 30,000 gallons per day evaporative capacity, it is possiblethat the entire flare assembly 115 may be mounted on the same skid orplate 230 as the concentrator 120.

Because most of the pumps, fluid lines, sensors and electronic equipmentare disposed on or are connected to the fluid concentrator assembly 120,the fluid scrubber 122 or the draft fan assembly 190, setup of theconcentrator 110 at a particular site does requires only minimalplumbing, mechanical, and electrical work at the site. As a result, theconcentrator 110 is relatively easy to install and to set up at (and todisassemble and remove from) a particular site. Moreover, because amajority of the components of the concentrator 110 are permanentlymounted to the skid 230, the concentrator 110 can be easily transportedon a truck or other delivery vehicle and can be easily dropped off andinstalled at particular location, such as next to a landfill flare.

FIG. 9 illustrates a schematic diagram of a control system 300 that maybe used to operate the concentrator 110 of FIG. 3. As illustrated inFIG. 9, the control system 300 includes a controller 302, which may be aform of digital signal processor type of controller, a programmablelogic controller (PLC) which may run, for example, ladder logic basedcontrol, or any other type of controller. The controller 302 is, ofcourse, connected to various components within the concentrator 110. Inparticular, the controller 302 is connected to the flare cap drive motor135, which controls the opening and closing operation of the flare cap134. The motor 135 may be set up to control the flare cap 134 to movebetween a fully open and a fully closed position. However, if desired,the controller 302 may control the drive motor 135 to open the flare cap134 to any of a set of various different controllable positions betweenthe fully opened and the fully closed position. The motor 135 may becontinuously variable if desired, so that the flare cap 134 may bepositioned at any desired point between fully open and fully closed.

Additionally, the controller 302 is connected to and controls theambient air inlet valve 306 disposed in the air pre-treatment assembly119 of FIG. 3 upstream of the venturi section 162 and may be used tocontrol the pumps 182 and 184 which control the amount of and the ratioof the injection of new liquid to be treated and the re-circulatingliquid being treated within the concentrator 110. The controller 302 maybe operatively connected to a sump level sensor 317 (e.g., a floatsensor, a non-contact sensor such as a radar or sonic unit, or adifferential pressure cell). The controller 302 may use a signal fromthe sump level sensor 317 to control the pumps 182 and 184 to maintainthe level of concentrated fluid within the sump 172 at a predeterminedor desired level. Also, the controller 302 may be connected to theinduced draft fan 190 to control the operation of the fan 190, which maybe a single speed fan, a variable speed fan or a continuouslycontrollable speed fan. In one embodiment, the induced draft fan 190 isdriven by a variable frequency motor, so that the frequency of the motoris changed to control the speed of the fan. Moreover, the controller 302is connected to a temperature sensor 308 disposed at, for example, theinlet of the concentrator assembly 120 or at the inlet of the venturisection 162, and receives a temperature signal generated by thetemperature sensor 308. The temperature sensor 308 may alternatively belocated downstream of the venturi section 162 or the temperature sensor308 may include a pressure sensor for generating a pressure signal.

During operation and at, for example, the initiation of the concentrator110, when the flare 130 is actually running and is thus burning landfillgas, the controller 302 may first turn on the induced draft fan 190 tocreate a negative pressure within the fluid scrubber 122 and theconcentrator assembly 120. The controller 302 may then or at the sametime, send a signal to the motor 135 to close the flare cap 134 eitherpartially or completely, to direct waste heat from the flare 130 intothe transfer pipe 140 and thus to the air pre-treatment assembly 119.Based on the temperature signal from the temperature sensor 308, thecontroller 302 may control the ambient air valve 306 (typically byclosing this valve partially or completely) and/or the flare capactuator to control the temperature of the gas at the inlet of theconcentrator assembly 120. Generally speaking, the ambient air valve 306may be biased in a fully open position (i.e., may be normally open) by abiasing element such as a spring, and the controller 302 may begin toclose the valve 306 to control the amount of ambient air that isdiverted into the air pre-treatment assembly 119 (due to the negativepressure in the air pre-treatment assembly 119), so as to cause themixture of the ambient air and the hot gases from the flare 130 to reacha desired temperature. Additionally, if desired, the controller 302 maycontrol the position of the flare cap 134 (anywhere from fully open tofully closed) and may control the speed of the induced draft fan 190, tocontrol the amount of gas that enters the air pre-treatment assembly 119from the flare 130. As will be understood, the amount of gas flowingthrough the concentrator 110 may need to vary depending on ambient airtemperature and humidity, the temperature of the flare gas, the amountof gas exiting the flare 130, etc. The controller 302 may thereforecontrol the temperature and the amount of gas flowing through theconcentrator assembly 120 by controlling one or any combination of theambient air control valve 306, the position of the flare cap 134 and thespeed of the induced draft fan 190 based on, for example, themeasurement of the temperature sensor 308 at the inlet of theconcentrator assembly 120. This feedback system is desirable because, inmany cases, the air coming out of a flare 130 is between 1200 and 1800degrees Fahrenheit, which may be too hot, or hotter than required forthe concentrator 110 to operate efficiently and effectively.

In any event, as illustrated in FIG. 9, the controller 302 may also beconnected to a motor 310 which drives or controls the position of theventuri plate 163 within the narrowed portion of the concentratorassembly 120 to control the amount of turbulence caused within theconcentrator assembly 120. Still further, the controller 302 may controlthe operation of the pumps 182 and 184 to control the rate at which (andthe ratio at which) the pumps 182 and 184 provide re-circulating liquidand new waste fluid to be treated to the inputs of the quencher 159 andthe venturi section 162. In one embodiment, the controller 302 maycontrol the ratio of the re-circulating fluid to new fluid to be about10:1, so that if the pump 184 is providing 8 gallons per minute of newliquid to the input 160, the re-circulating pump 182 is pumping 80gallons per minute. Additionally, or alternatively, the controller 302may control the flow of new liquid to be processed into the concentrator(via the pump 184) by maintaining a constant or predetermined level ofconcentrated liquid in the sump 172 using, for example, the level sensor317. Of course, the amount of liquid in the sump 172 will be dependenton the rate of concentration in the concentrator, the rate at whichconcentrated liquid is pumped from or otherwise exists the sump 172 viathe secondary re-circulating circuit and the rate at which liquid fromthe secondary re-circulating circuit is provided back to the sump 172,as well as the rate at which the pump 182 pumps liquid from the sump 172for delivery to the concentrator via the primary re-circulating circuit.

If desired, one or both of the ambient air valve 306 and the flare cap134 may be operated in a fail-safe open position, such that the flarecap 134 and the ambient air valve 306 open in the case of a failure ofthe system (e.g., a loss of control signal) or a shutdown of theconcentrator 110. In one case, the flare cap motor 135 may be springloaded or biased with a biasing element, such as a spring, to open theflare cap 134 or to allow the flare cap 134 to open upon loss of powerto the motor 135. Alternatively, the biasing element may be thecounter-weight 137 on the flare cap 134 may be so positioned that theflare cap 134 itself swings to the open position under the applied forceof the counter-weight 137 when the motor 135 loses power or loses acontrol signal. This operation causes the flare cap 134 to open quickly,either when power is lost or when the controller 302 opens the flare cap134, to thereby allow hot gas within the flare 130 to exit out of thetop of the flare 130. Of course, other manners of causing the flare cap134 to open upon loss of control signal can be used, including the useof a torsion spring on the pivot point 136 of the flare cap 134, ahydraulic or pressurized air system that pressurizes a cylinder to closethe flare cap 134, loss of which pressure causes the flare cap 134 toopen upon loss of the control signal, etc.

Thus, as will be noted from the above discussion, the combination of theflare cap 134 and the ambient air valve 306 work in unison to protectthe engineered material incorporated into the concentrator 110, aswhenever the system is shut down, the flare cap and the air valve 306automatically immediately open, thereby isolating hot gas generated inthe flare 130 from the process while quickly admitting ambient air tocool the process.

Moreover, in the same manner, the ambient air valve 306 may be springbiased or otherwise configured to open upon shut down of theconcentrator 110 or loss of signal to the valve 306. This operationcauses quick cooling of the air pre-treatment assembly 119 and theconcentrator assembly 120 when the flare cap 134 opens. Moreover,because of the quick opening nature of the ambient air valve 306 and theflare cap 134, the controller 302 can quickly shut down the concentrator110 without having to turn off or effect the operation of the flare 130.

Furthermore, as illustrated in the FIG. 9, the controller 302 may beconnected to the venturi plate motor 310 or other actuator which movesor actuates the angle at which the venturi plate 163 is disposed withinthe venturi section 162. Using the motor 310, the controller 302 maychange the angle of the venturi plate 163 to alter the gas flow throughthe concentrator assembly 120, thereby changing the nature of theturbulent flow of the gas through concentrator assembly 120, which mayprovide for better mixing of the and liquid and gas therein and obtainbetter or more complete evaporation of the liquid. In this case, thecontroller 302 may operate the speed of the pumps 182 and 184 inconjunction with the operation of the venturi plate 163 to provide foroptimal concentration of the wastewater being treated. Thus, as will beunderstood, the controller 302 may coordinate the position of theventuri plate 163 with the operation of the flare cap 134, the positionof the ambient air or bleed valve 306, and the speed of the inductionfan 190 to maximize wastewater concentration (turbulent mixing) withoutfully drying the wastewater so as to prevent formation of dryparticulates. The controller 302 may use pressure inputs from thepressure sensors to position the venturi plate 163. Of course, theventuri plate 163 may be manually controlled or automaticallycontrolled.

The controller 302 may also be connected to a motor 312 which controlsthe operation of the damper 198 in the gas re-circulating circuit of thefluid scrubber 122. The controller 302 may cause the motor 312 or othertype of actuator to move the damper 198 from a closed position to anopen or to a partially open position based on, for example, signals frompressure sensors 313, 315 disposed at the gas entrance and the gas exitof the fluid scrubber 122. The controller 302 may control the damper 198to force gas from the high pressure side of the exhaust section 124(downstream of the induced draft fan 190) into the fluid scrubberentrance to maintain a predetermined minimum pressure difference betweenthe two pressure sensors 313, 315. Maintaining this minimum pressuredifference assures proper operation of the fluid scrubber 122. Ofcourse, the damper 198 may be manually controlled instead or in additionto being electrically controlled.

Thus, as will be understood from the above discussion, the controller302 may implement one or more on/off control loops used to start up orshut down the concentrator 110 without affecting the operation of theflare 130. For example, the controller 302 may implement a flare capcontrol loop which opens or closes the flare cap 134, a bleed valvecontrol loop which opens or begins to close the ambient air valve 306,and an induced draft fan control loop which starts or stops the induceddraft fan 190 based on whether the concentrator 110 is being started orstopped. Moreover, during operation, the controller 302 may implementone or more on-line control loops which may control various elements ofthe concentrator 110 individually or in conjunction with one another toprovide for better or optimal concentration. When implementing theseon-line control loops, the controller 302 may control the speed ofinduced draft fan 190, the position or angle of the venturi plate 163,the position of the flare cap 134 and or the position of the ambient airvalve 306 to control the fluid flow through the concentrator 110, and/orthe temperature of the air at the inlet of the concentrator assembly 120based on signals from the temperature and pressure sensors. Moreover,the controller 302 may maintain the performance of the concentrationprocess at steady-state conditions by controlling the pumps 184 and 182which pump new and re-circulating fluid to be concentrated into theconcentrator assembly 120. Still further, the controller 302 mayimplement a pressure control loop to control the position of the damper198 to assure proper operation of the fluid scrubber 122. Of course,while the controller 302 is illustrated in FIG. 9 as a single controllerdevice that implements these various control loops, the controller 302could be implemented as multiple different control devices by, forexample, using multiple different PLCs.

As will be understood, the concentrator 110 described herein directlyutilizes hot waste gases in processes after the gases have beenthoroughly treated to meet emission standards, and so seamlesslyseparates the operational requirements of the process that generates thewaste heat from the process which utilizes the waste heat in a simple,reliable and effective manner.

In addition to being an important component of the concentrator 110during operation of the concentrator 110, the automated or manuallyactuated flare cap 134 described herein can be used in a standalonesituation to provide weather protection to a flare or to a flare and aconcentrator combination when the flare stands idle. With the flare cap134 closed, the interior of the metal shell of the flare 130 along withthe refractory, burners and other critical components of the flareassembly 115 and the heat transfer assembly 117 are protected fromcorrosion and general deterioration related to exposure to the elements.In this case, the controller 302 may operate the flare cap motor 135 tokeep the flare cap 134 fully open or partially closed during idling ofthe flare 130. Moreover, beyond using a flare cap 134 that closesautomatically when the flare 130 shuts down or that opens automaticallywhen the flare 130 is ignited, a small burner, such as the normal pilotlight, may be installed inside of the flare 130 and may be run when theflare 130 is shut down but while the flare cap 134 held closed. Thissmall burner adds further protection against deterioration of flarecomponents caused by dampness, as it will keep the interior of the flare130 dry. An example of a stand alone flare that may use the flare cap134 described herein in a stand-alone situation is a stand-by flareinstalled at a landfill to ensure gas control when a landfill gas fueledpower plant is off-line.

While the liquid concentrator 110 has been described above as beingconnected to a landfill flare to use the waste heat generated in thelandfill flare, the liquid concentrator 110 can be easily connected toother sources of waste heat. For example, FIG. 10 illustrates theconcentrator 110 modified so as to be connected to an exhaust stack of acombustion engine plant 400 and to use the waste heat from the engineexhaust to perform liquid concentration. While, in one embodiment, theengine within the plant 400 may operate on landfill gas to produceelectricity, the concentrator 110 can be connected to run with exhaustfrom other types of engines, including other types of combustionengines, such as those that operate on gasoline, diesel fuel, etc.

Referring to FIG. 10, exhaust generated in an engine (not shown) withinthe plant 400 is provided to a muffler 402 on the exterior of the plant400 and, from there, enters into a combustion gas exhaust stack 404having a combustion gas exhaust stack cap 406 disposed on the topthereof. The cap 406 is essentially counter-weighted to close over theexhaust stack 404 when no exhaust is exiting the stack 404, but iseasily pushed up by the pressure of the exhaust when exhaust is leavingthe stack 404. In this case, a Y-connector is provided within theexhaust stack 404 and operates to connect the stack 404 to a transferpipe 408 which transfers exhaust gas (a source of waste heat) from theengine to an expander section 410. The expander section 410 mates withthe quencher 159 of the concentrator 110 and provides the exhaust gasfrom the engine directly to the concentrator assembly 120 of theconcentrator 110. It is typically not necessary to include an air bleedvalve upstream of the concentrator section 120 when using engine exhaustas a source of waste heat because exhaust gas typically leaves an engineat less than 900 degrees Fahrenheit, and so does not need to be cooledsignificantly before entering the quencher 159. The remaining parts ofthe concentrator 110 remain the same as described above with respect toFIGS. 3-8. As a result, it can be seen that the liquid concentrator 110can be easily adapted to use various different sources of waste heatwithout a lot of modification.

Generally, when controlling the liquid concentrator 110 of FIG. 10, thecontroller will turn on the induced draft fan 190 while the engine inthe plant 400 is running. The controller will increase the speed of theinduced draft fan 190 from a minimal speed until the point that most orall of the exhaust within the stack 404 enters the transfer pipe 408instead of going out of the top of the exhaust stack 404. It is easy todetect this point of operation, which is reached when, as the speed ofthe induced draft fan 190 is increased, the cap 406 first sits back downon the top of the stack 404. It may be important to prevent increasingthe speed of the induced draft fan 190 above this operational point, soas to not create any more of a negative pressure within the concentrator110 than is necessary, and thereby assuring that the operation of theconcentrator 110 does not change the back pressure and, in particular,create undesirable levels of suction experienced by the engine withinthe plant 400. Changing the back pressure or applying suction within theexhaust stack 404 may adversely effect the combustion operation of theengine, which is undesirable. In one embodiment, a controller (not shownin FIG. 10), such as a PLC, may use a pressure transducer mounted in thestack 404 close to the location of the cap 406 to continuously monitorthe pressure at this location. The controller can then send a signal tothe variable frequency drive on the induced draft fan 190 to control thespeed of the induced draft fan 190 to maintain the pressure at adesirable set point, so as to assure that undesirable back pressure orsuction is not being applied on the engine.

FIGS. 11 and 12 illustrate a side cross-sectional view, and a topcross-sectional view, of another embodiment of a liquid concentrator500. The concentrator 500 is shown in a generally vertical orientation.However, the concentrator 500 shown in FIG. 11 may be arranged in agenerally horizontal orientation or a generally vertical orientationdepending on the particular constraints of a particular application. Forexample, a truck mounted version of the concentrator may be arranged ina generally horizontal orientation to allow the truck-mountedconcentrator to pass under bridges and overpasses during transport fromone site to another. The liquid concentrator 500 has a gas inlet 520 anda gas exit 522. A flow corridor 524 connects the gas inlet 520 to thegas exit 522. The flow corridor 524 has a narrowed portion 526 thataccelerates the gas through the flow corridor 524. A liquid inlet 530injects a liquid into the gas stream prior to the narrowed portion 526.In contrast to the embodiment of FIG. 1, the narrowed portion 526 of theembodiment of FIG. 11 directs the gas-liquid mixture into a cyclonicchamber 551. The cyclonic chamber 551 enhances the mixing of the gas andliquid while also performing the function of the demister in FIG. 1. Thegas-liquid mixture enters the cyclonic chamber 551 tangentially (seeFIG. 12) and then moves in a cyclonic manner through the cyclonicchamber 551 towards a liquid outlet area 554. The cyclonic circulationis facilitated by a hollow cylinder 556 disposed in the cyclonic chamber551 that conducts the gas to the gas outlet 522. The hollow cylinder 556presents a physical barrier and maintains the cyclonic circulationthroughout the cyclonic chamber 551 including the liquid outlet area554.

As the gas-liquid mixture passes through the narrowed portion 526 of theflow corridor 524 and circulates in the cyclonic chamber 551, a portionof the liquid evaporates and is absorbed by the gas. Furthermore,centrifugal force accelerates movement of entrained liquid droplets inthe gas towards the side wall 552 of the cyclonic chamber 551 where theentrained liquid droplets coalesce into a film on the side wall 552.Simultaneously, centripetal forces created by an induction fan 550collect the demisted gas flow at the inlet 560 of the cylinder 556 anddirect the flow to the gas outlet 522. Thus, the cyclonic chamber 551functions both as a mixing chamber and a demisting chamber. As theliquid film flows towards the liquid outlet area 554 of the chamber dueto the combined effects of the force of gravity and the cyclonic motionwithin cyclonic chamber 551 toward the liquid outlet area 554, thecontinuous circulation of the gas in the cyclonic chamber 551 furtherevaporates a portion of the liquid film. As the liquid film reaches theliquid outlet area 554 of the cyclonic chamber 551, the liquid isdirected through a re-circulating circuit 542. Thus, the liquid isre-circulated through the concentrator 500 until a desired level ofconcentration is reached. A portion of the concentrated slurry may bedrawn off through an extraction port 546 when the slurry reaches thedesired concentration (this is called blowdown). Fresh liquid is addedto the circuit 542 through a fresh liquid inlet 544 at a rate equal tothe rate of evaporation plus the rate of slurry drawn off through theextraction port 546.

As the gas circulates in the cyclonic chamber 551, the gas is cleansedof entrained liquid droplets and drawn towards the liquid discharge area554 of the cyclonic chamber 551 by the induction fan 550 and towards aninlet 560 of the hollow cylinder 556. The cleansed gas then travelsthrough the hollow cylinder 556 and finally vents through the gas exit522 to the atmosphere or further treatment (e.g., oxidization in aflare).

FIG. 13 illustrates a schematic view of a distributed liquidconcentrator 600 configured in a manner that enables the concentrator600 to be used with many types of sources of waste heat, even sources ofwaste heat that are located in places that are hard to access, such ason the sides of buildings, in the middle of various other equipment,away from roads or other access points, etc. While the liquidconcentrator 600 will be described herein as being used to process orconcentrate leachate, such as leachate collected from a landfill, theliquid concentrator 600 could be used to concentrate other types ofliquids as well or instead including many other types of wastewaters.

Generally speaking, the liquid concentrator 600 includes a gas inlet620, a gas outlet or a gas exit 622, a flow corridor 624 connecting thegas inlet 620 to the gas exit 622 and a liquid re-circulating system625. A concentrator section has a flow corridor 624 that includes aquencher section 659 including the gas inlet 620 and a fluid inlet 630,a venturi section 626 disposed downstream of the quencher section 659,and a blower or draft fan 650 connected downstream of the venturisection 626. The fan 650 and a flooded elbow 654 couple a gas outlet ofthe concentrator section (e.g., an outlet of the venturi section 626) toa piping section 652. The flooded elbow 654, in this case, forms a 90degree turn in the flow corridor 624. However, the flooded elbow 654could form a turn that is less than or more than 90 degrees if desired.The piping section 652 is connected to a demister, in this caseillustrated in the form of a crossflow scrubber 634, which is, in turn,connected to a stack 622A having the gas exit 622.

The re-circulating system 625 includes a sump 636 coupled to a liquidoutlet of the crossflow scrubber 634, and a re-circulating or recyclepump 640 coupled between the sump 636 and a piping section 642 whichdelivers re-circulated fluid to the fluid inlet 630. A process fluidfeed 644 also delivers leachate or other liquid to be processed (e.g.,concentrated) to the fluid inlet 630 to be delivered to the quenchersection 659. The re-circulating system 625 also includes a liquidtakeoff 646 connected to the piping section 642, which delivers some ofthe recycled fluid (or concentrated fluid) to a storage, settling andrecycle tank 649. The heavier or more concentrated portions of theliquid in the settling tank 649 settle to the bottom of the tank 649 assludge, and are removed and transported for disposal in concentratedform. Less concentrated portions of the liquid in the tank 649 aredelivered back to the sump 636 for reprocessing and furtherconcentration, as well as to assure that an adequate supply of liquid isavailable at the liquid inlet 630 at all times so to ensure that dryparticulate is not formed. Dry particulate can form at reduced ratios ofprocess fluid to hot gas volumes.

In operation, the quencher section 659 mixes fluid delivered from theliquid inlet 630 with gas containing waste heat collected from, forexample, an engine muffler and stack 629 associated with an internalcombustion engine (not shown). The liquid from the fluid inlet 630 maybe, for example, leachate to be processed or concentrated. Asillustrated in FIG. 13, the quencher section 659 is connected verticallyabove the venturi portion 626 which has a narrowed portion that operatesto accelerate the flow of gas and liquid through a section of the fluidflow corridor 624 immediately downstream of the venturi portion 626 andupstream of the fan 650. Of course, the fan 650 operates to create a lowpressure region immediately downstream of the venturi portion 626,drawing gas from the stack 629 through the venturi portion 626 and theflooded elbow 654 and causing mixing of the gas and liquid.

As noted above, the quencher section 659 receives hot exhaust gas fromthe engine exhaust stack 629 and may be connected directly to anydesired portion of the exhaust stack 629. In this illustratedembodiment, the engine exhaust stack 629 is mounted on an outside of abuilding 631 that houses one or more electric power generators thatgenerate electric power using landfill gas as a combustion fuel. In thiscase, the quencher section 659 may be connected directly to a condensatetake off (e.g., a weep leg) associated with the stack 629 (i.e., a lowerportion of the exhaust stack 629). Here, the quencher section 659 may bemounted immediately below or adjacent to the stack 629 requiring only afew inches or at most a few feet of expensive, high temperature pipingmaterial to connect the two together. If desired, however, the quenchersection 659 may be coupled any other portion of the exhaust stack 629,including, for example, to the top or to a middle portion of the stack629 via appropriate elbows or takeoffs.

As noted above, the liquid inlet 630 injects a liquid to be evaporated(e.g., landfill leachate) into the flow corridor 624 through thequencher section 659. If desired, the liquid inlet 630 may include areplaceable nozzle for spraying the liquid into the quencher section659. The liquid inlet 630, whether or not equipped with a nozzle, mayintroduce the liquid in any direction, from perpendicular to parallel tothe gas flow as the gas moves through the flow corridor 624. Moreover,as the gas (and the waste heat stored therein) and liquid flow throughthe venturi portion 626, the venturi principle creates an acceleratedand turbulent flow that thoroughly mixes the gas and liquid in the flowcorridor 624 immediately downstream of the venturi section 626. As aresult of the turbulent mixing, a portion of the liquid rapidlyvaporizes and becomes part of the gas stream. This vaporization consumesa large amount of the heat energy within the waste heat as latent heatthat exits the concentrator system 600 as water vapor within the exhaustgas.

After leaving the narrowed portion of the venturi section 626, thegas/liquid mixture passes through the flooded elbow 654 where the flowcorridor 624 turns 90 degrees to change from a vertical flow to ahorizontal flow. The gas/liquid mixture flows past the fan 650 andenters a high pressure region at the downstream side of the fan 650,this high pressure region existing in the piping section 652. The use ofa flooded elbow 654 at this point in the system is desirable for atleast two reasons. First, the liquid at the bottom portion of theflooded elbow 654 reduces erosion at the turning point in the flowcorridor 624, which erosion would normally occur due to suspendedparticles within the gas/liquid mixture flowing at high rates of speedthrough a 90 degree turn and impinging at steep angles directly on thebottom surfaces of a conventional elbow were the flooded elbow 654 notemployed. The liquid in the bottom of the flooded elbow 654 absorbs theenergy in these particles and therefore prevents erosion on the bottomsurface of the flooded elbow 654. Still further, liquid droplets whichstill exist in the gas/liquid mixture as this mixture arrives at theflooded elbow 654 are more easily collected and removed from the flowstream if they impinge upon a liquid. That is, the liquid at the bottomof the flooded elbow 654 operates to collect liquid droplets impingingthereon because the liquid droplets within the flow stream are moreeasily retained when these suspended liquid droplets come into contactwith a liquid. Thus, the flooded elbow 654, which may have a liquidtakeoff (not shown) connected to, for example, the re-circulatingcircuit 625, operates to remove some of the process fluid droplets andcondensation from the gas/liquid mixture exiting the venturi section626.

Importantly, the gas/liquid mixture while passing through the venturisection 626 quickly approaches the adiabatic saturation point, which isat a temperature that is much lower than that of the gas exiting thestack 629. For example, while the gas exiting the stack 629 may bebetween about 900 and about 1800 degrees Fahrenheit, the gas/liquidmixture in all sections of the concentrator system 600 downstream of theventuri section 626 will generally be in the range of 150 degrees to 190degrees Fahrenheit, although it can range higher or lower than thesevalues based on the operating parameters of the system. As a result,sections of the concentrator system 600 downstream of the venturisection 626 do not need to be made of high temperature resistantmaterials and do not need to be insulated at all or to the degree thatwould be necessary for transporting higher temperature gases ifinsulation were to be applied for the purpose of more fully utilizingthe waste heat content of the inlet hot gas. Still further the sectionsof the concentrator system 600 downstream of the venturi section 626disposed in areas, such as along the ground that people will come intocontact with, without significant danger, or with only minimal exteriorprotection. In particular, the sections of the concentrator systemdownstream of the venturi section 626 may be made of fiberglass and mayneed minimal or no insulation. Importantly, the gas/liquid stream mayflow within the sections of the concentrator system downstream of theventuri section 626 over a relatively long distance while maintainingthe gas/liquid mixture therein at close to the adiabatic saturationpoint, thereby allowing the piping section 652 to easily transport theflow stream away from the building 631 to a more easily accessiblelocation, at which the other equipment associated with the concentrator600 can be conveniently disposed. In particular, the piping section 652may span 20 feet, 40 feet, or even longer while maintaining the flowtherein at close to the adiabatic saturation point. Of course, theselengths may be longer or shorter based on ambient temperature, the typeof piping and insulation used, etc. Moreover, because the piping section652 is disposed on the high pressure side of the fan 650, it is easierto remove condensation from this stream. In the example embodiment ofFIG. 13, the piping section 652 is illustrated as flowing past orbeneath an air cooler associated with the engines within the building631. However, the air cooler of FIG. 13 is merely one example of thetypes of obstructions that may be located close to the building 631which make it problematic to place all of the components of theconcentrator 600 in close proximity to the source of the waste heat (inthis case, the stack 629). Other obstructions could include otherequipment, vegetation such as trees, other buildings, inaccessibleterrain without roads or easy access points, etc.

In any event, the piping section 652 delivers the gas/liquid stream atclose to the adiabatic saturation point to the demister 634, which maybe, for example, a crossflow scrubber. The demister 634 operates toremove entrained liquid droplets from the gas/liquid stream. The removedliquid collects in the sump 636 which directs the liquid to the pump640. The pump 640 moves the liquid through the return line 642 of there-circulating circuit 625 back to the liquid inlet 630. In this manner,the captured liquid may be further reduced through evaporation to adesired concentration and/or re-circulated to prevent the formation ofdry particulate. Fresh liquid to be concentrated is input through thefresh liquid inlet 644. The rate of fresh liquid input into there-circulating circuit 625 should be equal to the rate of evaporation ofthe liquid as the gas-liquid mixture flows through the flow corridor 624plus the rate of liquid or sludge extracted from the settling tank 649(assuming the material within the settling tank 649 remains at aconstant level). In particular, a portion of the liquid may be drawn offthrough an extraction port 646 when the liquid in the re-circulatingcircuit 625 reaches a desired concentration. The portion of liquid drawnoff through the extraction port 646 may be sent to the storage andsettling tank 649 where the concentrated liquid is allowed to settle andseparate into its component parts (e.g., a liquid portion and asemi-solid portion). The semi-solid portion may be drawn from the tank649 and disposed of or further treated.

As noted above, the fan 650 draws the gas through a portion of the flowcorridor 624 under negative pressure and pushes gas through anotherportion of the flow corridor 624 under positive pressure. The quenchersection 659, venturi section 626, and fan 650 may be attached to thebuilding 631 with any type of connecting device and, as illustrated inFIG. 13, are disposed in close proximity to the source of waste heat.However the demister 634 and the gas outlet 622, as well as the settlingtank 649, may be located some distance away from the quencher section659, venturi section 626, and fan 650, at for example, an easy to accesslocation. In one embodiment, the demister 634 and the gas outlet 622 andeven the settling tank 649 may be mounted on a mobile platform such as apallet or a trailer bed.

FIGS. 14-16 illustrate another embodiment of a liquid concentrator 700which may be mounted on a pallet or trailer bed. In one embodiment, someof the components of the concentrator 700 may remain on the bed and beused to perform concentration activities, while others of thesecomponents may be removed and installed near a source of waste heat inthe manner illustrated in, for example, the embodiment of FIG. 13. Theliquid concentrator 700 has a gas inlet 720 and a gas exit 722. A flowcorridor 724 connects the gas inlet 720 to the gas exit 722. The flowcorridor 724 has a narrowed or venturi portion 726 that accelerates thegas through the flow corridor 724. Gas is drawn into a quencher section759 by an induction fan (not shown). A liquid inlet 730 injects a liquidinto the gas stream in the quencher section 759. Gas is directed fromthe venturi section 726 into the demister (or cross flow scrubber) 734by an elbow section 733. After exiting the demister 734, the gas isdirected to the gas exit 722 through a stack 723. Of course, asdescribed above, some of these components may be removed from the bedand installed in close proximity to a source of waste heat while othersof these components (such as the demister 734, the stack 723 and the gasexit 722) may remain on the bed.

As the gas-liquid mixture passes through the venturi portion 726 of theflow corridor 724, a portion of the liquid evaporates and is absorbed bythe gas, thus consuming a large portion of heat energy within the wasteheat as latent heat that exits the concentrator system 700 as watervapor within the exhaust gas.

In the embodiment shown in FIGS. 14-16, portions of the liquidconcentrator 700 may be disassembled and mounted on a pallet or trailerskid for transportation. For example, the quenching section 759 and theventuri section 726 may be removed from the elbow section 733, asillustrated by the dashed line in FIG. 14. Likewise, the stack 723 maybe removed from the induction fan 750 as illustrated by the dashed linein FIG. 14. The elbow section 733, demister 734, and induction fan 750may be secured on a pallet or trailer skid 799 as a unit. The stack 723may be secured separately to the pallet or trailer skid 799. Thequenching section 759 and venturi section 726 may also be secured to thepallet or trailer skid 799, or alternately transported separately. Thecompartmentalized construction of the liquid concentrator 700 simplifiestransportation of the liquid concentrator 700.

Turning now to FIG. 17, a liquid concentrator 800 includes an evaporatorassembly 801, which in one form includes a mixing corridor having amixing chamber 802 and an evaporator section 804, a cyclonic separator806, a sump 808, and a settling chamber 810. The mixing chamber isconnected to a source of gas, preferably heated gas, such as waste heatgas from a flare stack or exhaust from an internal combustion engine,turbine or any other suitable source of heated gases 812. A wastewatersupply pipe 814 also opens into the mixing chamber 802 to supplywastewater 816 into the mixing chamber. The wastewater 816 initiallymixes with gases 812 in the mixing chamber and then the mixture is drawnthrough the evaporator section 804 where the wastewater mixes morethoroughly with the gases and liquid from the wastewater evaporates intothe gases.

The evaporator section 804 preferably includes a venturi evaporator,which includes a narrow venturi section through which the gases areaccelerated and the corresponding static pressure drop induces thethorough mixing and rapid evaporation of the liquids from thewastewater, as in the form of the venturi section 162 of FIGS. 3 and 10,the narrowed portion 526 of FIG. 11, or the venturi section 626 of FIG.13. The evaporator section 804, however, may have other forms suitablefor evaporating water or other liquids from the wastewater, includingfor example, open flames, a draft tubes, or static mixing devices. Themixed wastewater and gases from the evaporator section 804 are thentransferred by a transfer conduit or duct 818, which preferably has alarger cross-sectional area than the venturi section, into the cyclonicseparator 806.

The cyclonic separator 806 is arranged to separate liquids and solidsfrom the gases that are received from the evaporator section 804 via thetransfer duct 818 by both gravity fallout of solids and any suspendedwastewater and also by centrifugal force of cyclonic motion of the gasesthrough the cyclonic separator. The cyclonic motion forces wastewaterand solids carried in the gases radially outwardly against theperipheral inner wall of the cyclonic separator, where they collect andrun down the wall by the force of gravity. In a preferred arrangementthe cyclonic separator 806 is in the form of a tubular vessel 807, suchas a cylindrical tower, with its axis 822 arranged substantiallyvertically. In other aspects the tubular vessel 807 may be square orhave other cross-sectional configurations, for example, hexagonal,octagonal, etc. Description as a tubular vessel 807 refers to the innerperiphery of the vessel and not necessarily to exterior portions of thevessel, which may be any shape or form without affecting the functionaltubularity of the interior of the vessel. Although the cyclonicseparator 806 is preferably vertically oriented, it may be tilted out ofvertical a few degrees one way or the other and still be substantiallyvertical. For the present description, an important aspect is that thecyclonic separator 806 be oriented vertically enough to allow wastewaterand solids that are separated from the gases to drop by the force ofgravity down to the sump 808 while the gases are ejected through theexhaust outlet 820 at an upper end of the vessel. The evaporator section804 is operatively connected to a lower portion of the tubular vessel807 by the transfer duct 818 or any effective means and may be directlyconnected to or directly exhaust into the cyclonic separator without anintervening duct portion. Preferably, the inlet of the transfer duct 818into the cyclonic separator 806 is arranged to be tangential to the wallto promote spiral movement of the gases through the tubular vessel 807as depicted in the drawings.

The sump 808 is disposed below the cyclonic separator 806 and in oneembodiment as shown in FIG. 17 is formed by the bottom end of thetubular vessel 807. The sump 808 is arranged to collect the wastewaterand solids that are separated from the gases and fall by gravitydownwardly upon the interior wall of the tubular vessel 807. Someaspects the sump 808 may be partially separated from the remainingportions of the interior of the cyclonic separator 806 such as bybaffles or duct or conduits as long as the sump is able to collect thewastewater and solids that fall by the force of gravity downwardlythrough the cyclonic separator 806.

The settling chamber 810 is separated from the sump 808 and ishydraulically connected to the sump so as to be able to receive solidsand wastewater from the sump 808. The settling chamber 810 may beseparated from the sump 808 by any mechanism sufficient to cause fluidflow in the settling chamber to be relatively quiescent in relation tofluid flow in the sump.

In a preferred arrangement as shown in FIG. 17, the settling chamber 810is remote from the cyclonic separator 806 and hydraulically connected tothe sump 808 by a conduit 824. Further the settling chamber 810 ispreferably arranged to have a liquid head level 826 that is higher thana liquid head level 828 in the sump. For example, in one preferredarrangement the liquid head level 826 in the settling chamber 810 isdesigned to be approximately half-way up the height of the cyclonicseparator 806, whereas the liquid head level 828 in the sump 808 isdesigned to be near the bottom of the cyclonic separator. In thisarrangement, it is useful to have a pump 830 operatively disposed alongthe conduit 824, such as by being disposed in-line with the conduit, inorder to pump the wastewater and solids from the sump 808 up to thehigher head level 826 in the settling chamber 810. The settling chamber810 may take any form sufficient to allow quiescent settling of thesolids from the wastewater. One preferred settling chamber design is anImhoff tank, which is a known separator having two chambers, an upperchamber 832 and a lower chamber 834 and a restricted opening 836 betweenthe upper chamber and the lower chamber. Preferably the upper chamber832 and lower chamber 834 each has the form of a substantiallycone-bottom tank, although many other forms and shapes of settlingchambers would be capable of performing the same or similar functions.The conduit 824 is attached to a liquid inlet 837 into the settlingchamber 810, which may be for example directly into the upper chamber832 of the Imhoff tank. The settling chamber 810 may take other forms toachieve other desired design objectives. For example, in anotherarrangement, the Imhoff tank is replaced by an inclined plate separatorand/or a simple single cone-bottom tank, depending on thecharacteristics the solids to be settled and the desired end result.

A recirculation conduit 838, such as a pipe or tube, is arranged totransfer wastewater from an upper portion of the settling chamber 810back to the mixing chamber 802. The recirculation conduit 838 may have aseparate liquid inlet 840 into the mixing chamber 802 and/or the conduit838 may connect up with the wastewater supply conduit 814 therebyallowing the wastewater from the settling chamber 810 to mix with thewastewater 816 either prior to entering the mixing chamber 802 or in themixing chamber 802. The liquid inlet 840 forms in one embodiment a lowpressure injection port, which preferably injects the re-circulatedwastewater into the mixing chamber 802 at a pressure of about 10 psig orless, more preferably about 5 psig or less, and most preferably at apressure at about 2 psig. In a preferred arrangement, the liquid headlevel 826 of the settling chamber 810 is higher than the elevation ofthe liquid inlet 840 so that the re-circulated wastewater will travelthrough the conduit 838 back to the liquid inlet opening 840 under theforce of gravity alone. However a pump 842 may be placed functionally inline with the conduit 838 to assist in moving the re-circulatedwastewater from the settling tank 810 to the liquid inlet 840, in whichcase the liquid head level 826 of the settling chamber 810 may bedisposed below the elevation of the liquid inlet 840. Other fluidtransfer and pressure control devices may also be functionally disposedin the conduit 838 as necessary to achieve other design requirements.The low pressure projection port for liquid inlet 840 preferably doesnot include a spray nozzle and may include a baffle 844 to help deflectand/or otherwise disperse the flow of re-circulated wastewater from theliquid inlet to promote better and faster mixing of the re-circulatedwastewater with the gases 812 in the mixing chamber 802. A spray nozzle846 may, however, optionally be included over the liquid inlet 840 tofurther or alternatively promote mixing of the re-circulated wastewaterwith the gases 812.

The tubular vessel 807 is substantially unobstructed between inlet 850of the duct 818 into lower portion of the tubular vessel and the exhaustoutlet 820, which is preferably disposed at the very top end of thetubular vessel 807. By substantially unobstructed it is meant there areno significant obstruction such as baffles or venturi sections or otherrestrictions between the inlet 850 and the exhaust outlet 820 that wouldprevent gases from freely flowing from the inlet 850 to the exhaustoutlet 820. There may, however, be various minor obstructions such asdoorways, nozzles, and/or fans and still be substantially unobstructed,as long as the flow of gases from the inlet 850 to the exhaust outlet820 is not significantly blocked by any structures on the interior ofthe cyclonic separator 806.

A fan 852 draws the gases from the inlet 850 upwardly toward the exhaustoutlet 820 in any sufficient matter. In one arrangement, the fan 852 isdisposed inside an upper portion of the tubular body as shown in FIG.17. In another arrangement fan 852 may be disposed in the exhaust outlet820. In a further embodiment shown in dashed lines in FIG. 17, the fan852 is remote from the flowpath of the gases through the liquidconcentrator 800, such as being located outside of the cyclonicseparator 806, and operatively connected with the interior of thecyclonic separator 806, for example, by a duct 853. Preferably, the duct853 extends from the exhaust outlet 820 of cyclonic separator 806 to aninlet of the fan 852. The fan 852 draws hot gases and evaporated liquidfrom the exhaust outlet 820 and injects the hot exhaust gases andevaporated liquid into an exhaust duct 855, which discharges the hotgases and evaporated liquid to atmosphere or any desirable vaportreatment or vapor recovery system (neither shown). Additionally, thefan 852 in this embodiment preferably is not supported by the tubularvessel 807, and may be spatially separated from the tubular vessel. Inone exemplary arrangement, the fan 852 is mounted on the ground or atgrade level either adjacent to or spaced from the tubular vessel 807,and the duct 853 connects an inlet of the fan 852 with the exhaust duct854, which can eliminate any need for significant added structuralsupports for the fan 852 and/or vibration loads on the tubular vessel807. Locating the fan 852 remote from the flow path of the gases andwastewater also minimizes the need for extended structural supports andsimplifies installation and maintenance activities for the fan 852thereby reducing first costs and maintenance expenses.

The liquid concentrator 800 may optionally include structures designedto help maintain the interior of the cyclonic separator 806 and/or themixing corridor, clean and free from scale and/or sludge build up. Forone maintenance feature, clean water injection ports 854 are disposedinside one or more of the mixing chamber 802 the evaporator section 804,the duct 818, and the cyclonic separator 806 to help wash the interiorthereof. Preferably, each clean water injection port 854 has a nozzle856 that is arranged to spray pressurized clean water against areas ofthe interior of the various structures that are prone to build up ofscale and/or sludge.

Another maintenance feature adapted for allowing easy cleaning of theliquid concentrator 800 is a door 858 covering an opening into thecyclonic separator 806. The door 858, which may be the same as the door200 shown in FIG. 7, is attached to the cyclonic separator with one ormore hinges 860 and includes a latch 862 for latching the door in aclosed position covering the opening. The latch is preferably a quickrelease latch of any form readily known in the art. A seal 864 isarranged around the opening to form a seal between the door 858 and thevessel 807 when the door is closed. In a preferable arrangement, thedoor 858 is sized to receive a person easily therethrough, such as bybeing approximately two feet in diameter or square or any other shapeand size designed to allow ready access of a person into the interior ofthe tubular vessel 807.

In FIG. 18, another liquid concentrator 900 is shown which includesadditional aspects of the design that overcome some of the limitationswith the prior art pointed out herein-above. The liquid concentrator 900has many features that are substantially identical to the liquidconcentrator 800 and therefore substantially similar or identicalfeatures are given the same reference numbers as given with liquidconcentrator 800. The liquid concentrator 900 includes an evaporatorassembly 801 with a mixing corridor having a mixing chamber 802 and anevaporator section 804. The mixing chamber 802 receives wastewater 816via a wastewater feed conduit 814 and gas 812, such as heated waste gasfrom a flair stack or engine exhaust. The evaporator section 804 isconnected with the mixing chamber 802 and is arranged to mix thewastewater with the gas and evaporate liquids from the wastewater. Theevaporator section 804 is preferably a venturi evaporator as previouslydescribed herein. The evaporator section 804 is connected to the bottomof the cyclonic separator 806 by the duct 818. The duct 818 is connectedto the cyclonic separator 806 by a port that is tangentially aligned soas to dispense the mixed wastewater and gases into the cyclonicseparator, tangentially whereby the gases will travel through thecyclonic separator in a spiral or cyclonic path. Other portions of thecyclonic separator 806 are preferably substantially the same aspreviously described herein and will not be repeated for the sake ofbrevity.

Unlike the liquid concentrator 800, the liquid concentrator 900 includesa settling chamber 910 disposed directly beneath the bottom end of thetubular vessel 807 for receiving the solids and liquids that fall out ofthe gases in the cyclonic separator. In this design there is no separatesump between the tubular vessel 807 and the settling chamber 910. Ratherthe settling chamber 910 functions as both a sump and settling chamberin a single combined chamber.

An opening 966 at the bottom of the cyclonic separator 806 allows thesolids and wastewater to fall by gravity from the interior the tubularvessel 807 into the settling chamber 910. The opening 966 has a width W1adjacent the settling chamber 910 and the settling chamber 910 has asecond width W2 adjacent the opening 966, wherein the width W2 is largerthan the width W1. Having the width of the settling chamber W2 largerthan the width W1 of the opening leading into the settling chamberallows both the high velocity movement of gases through the cyclonicseparator 806, which promotes evaporation and helps prevent build up ofsolids therein, while simultaneously providing for more quiescent flowof the wastewater through the settling chamber 910 to allow the solidsto settle to the bottom thereof as the wastewater is drawn towardrecirculation conduit 838. In a preferred design, the cyclonic separator806 has a cylindrical inner surface, the first width W1 comprises aninside diameter of the cyclonic separator, and the opening 966corresponds to the inside diameter of the cyclonic separator. However,the opening 966 may be restricted or narrower than other portions of theinterior of the cyclonic separator 806, such as with a peripheral ledgeor collar. Further, baffles or grates (not shown) optionally are placedacross the opening 966 to further separate the high velocity motion ofthe gases moving through the cyclonic separator 806 from the quiescent,lower-velocity motion of liquids through the settling chamber 910 to therecirculation conduit 838. The shape of the settling chamber can takevarious forms, such as rectangular, oval, circular, egg shaped, etc.,and may have a flat bottom or may have a slanted bottom to directsettled solids and sludge toward a specific extraction point. In onepreferred embodiment, the settling chamber 910 has a circular shapeadjacent the opening 966 and the width W2 corresponds with an insidediameter of the settling chamber adjacent the opening 966. In anotherembodiment, the settling chamber 910 may be rectangular and the width W2is an inside width across a rectangular shape. The particular shapes ofthe opening 966 between the interior of the cyclonic separator 806 andthe settling chamber 810 may be varied as required to meet certaindesign requirements, such as available area and space for layout of theliquid concentrator 900. The use of a larger width W2 for the settlingchamber 910 allows the velocity of movement of wastewater from theopening 966 towards the recirculation conduit 838 to be slower than ifthe settling chamber were simply the bottom end of the tubular vessel807, thereby allowing or providing more opportunity for solids to settleto the bottom of the settling chamber.

FIG. 19 shows another liquid concentrator 1000 with many identical orsimilar features to the liquid concentrators 800 and 900, which arenumbered the same as previously. The liquid concentrator 1000 includesan evaporator assembly 801 with a mixing corridor having a mixingchamber 802 and evaporator section 804 connected to the mixing chamber802, and a transfer duct 818 that connects the mixing chamber 804 with alower end of a cyclonic separator 1006. Wastewater 816 is injected intothe mixing chamber 802 with a wastewater supply conduit 814, and gas,such as heated waste gases 812, is supplied into the mixing chamber 802.The evaporator section 804 is preferably a venturi evaporator aspreviously described, whereby gas and wastewater are accelerated throughthe venturi and thoroughly mixed such that liquid from the wastewater isevaporated into the gases. The mixture of gases and wastewater aretransferred via the transfer duct 818 into the cyclonic separator 1006where the gases and any suspended solids and wastewater travelcyclonically to separate the solids and wastewater from the gases in amanner generally similar to that previously described herein.

A significant difference between the liquid concentrator 1000 and theliquid concentrators 800 and 900 is that the cyclonic separator 1006 isseparated into a lower chamber 1070 and an upper chamber 1072 by anysuitable means, such as a divider 1074 extended across a middle portionof the tubular vessel 807. The divider 1074 prevents liquids and solidsfrom falling from the upper chamber 1072 down into the lower chamber1070 inside the cyclonic separator 1006.

A duct 1076 allows gas flow from the lower chamber 1070 to the upperchamber 1072 around the divider 1074, whereby gas from the lower chambercan move from the lower chamber into to the upper chamber. Preferablythe duct 1076 as a first opening 1078 through a sidewall of the tubularvessel 807 in the lower chamber 1070, a second opening 1080 through thesidewall of the tubular vessel into the upper chamber 1072, and at leastsome curve on the exterior side of the cyclonic separator to connect thetwo openings. Thus, in one arrangement the duct 1076 has a generallyU-shaped configuration as shown in FIG. 19, which thereby allows gas toflow out of the lower chamber, up and around the divider 1074, and backinto the upper chamber. The duct 1076 may alternatively be completelycontained inside the tubular vessel 807, in which case the first andsecond openings 1078, 1080 through the sidewall of the tubular vessel807 would be eliminated.

A fan 1082 is preferably operatively in line with the duct 1076 so as todraw the gases with a negative pressure from the transfer duct 818 intothe lower chamber 1070 and from there through the opening 1078 into theduct 1076. The fan 1082 then pushes the air with positive pressurethrough the opening 1080 into the upper chamber 1072, and from the upperchamber out through the exhaust outlet 820 disposed at a top end of thecyclonic separator 1006. In a preferred arrangement, the ducts 818 and1076 and the openings 1078 and 1080 are directed tangentially along aninner diameter of the cyclonic separator 1006 in order to inducecyclonic motion of the gases through both the lower chamber 1070 and theupper chamber 1072. Preferably, the first opening 1078 of the conduit1076 is disposed above the sump 808 toward an upper end of the lowerchamber 1070 and the second opening 1080 of the conduit 1076 is disposedabove the second sump 1084 nearer the lower end of the upper chamber1072. The opening 1080 of the duct 1076 is preferably located above amaximum operating level of liquid in the second sump 1084.

The cyclonic separator 1006 forms a first sump 808 at a bottom end ofthe lower chamber 1070 and a second sump 1084 at the bottom of the upperchamber 1072, wherein the sumps 808 and 1084 receive and collectwastewater and solids that separate out from the gases and falldownwardly as the gases move upwardly through the lower and upperchambers 1070 and 1072. Preferably, the cyclonic separator 1006 isformed of the single cylindrical vessel 807 that is vertically orientedand defines both the upper chamber 1072 and the lower chamber 1070, andthe divider 1074 is formed of a solid plate occluding the entirecross-sectional area of the cyclonic separator 1006, such as spanningthe inner diameter of the cylindrical vessel 807. However the upperchamber 1072 and lower chamber 1070 need not be formed by a singlecylindrical vessel and may be separated from each other, for example, bybeing spaced apart as first and second vessels that are connected by asuitable duct 1076.

Recirculation conduits 838 and 1086 are connected to the lower sump 808and upper sump 1084, respectively, to remove wastewater and/or sludgeand collected solids therefrom. The recirculation conduits 838 and 1086may transfer the sludge and wastewater to any desired location for anydesired purpose. In a preferred embodiment, the recirculation conduits838 and 1086 re-circulate the wastewater and sludge back to the mixingchamber 802 via, for example, the wastewater supply conduit 814, forrecirculation through the liquid concentrator 1000 and further removalof water and/or other liquids therefrom during the second and subsequentpasses through the liquid concentrator. Additionally, the recirculationconduits 838 and 1086 may be directed to other processing or wasteremoval equipment as desired.

The liquid concentrator 1000 preferably includes cleaning andmaintenance features, such as the clean water injection ports 854directed into one or more of the upper chamber 1072, the lower chamber1070, and the mixing chamber 854, and/or other portions of the liquidconcentrator. The water injection port 854 may be used to inject cleanwater into the respective chambers to rinse the interior thereof aspreviously described herein. Further, one or more doors 858, aspreviously described herein, may be disposed over openings through thewall of the cyclonic separator 1006 to provide access by a persontherein to allow cleaning of the interior of the upper chamber and/orlower chamber and/or other portions of the liquid concentrator 1000.

Turning to FIG. 20, another liquid concentrator 1100 includes anevaporator section 804 and a cyclonic separator 1106. The evaporatorsection 804 preferably has a venturi evaporator and other features thesame as previously described herein. The cyclonic separator 1106 issimilar to the separator 806, except that the inlet 850 of the duct 818is located near a top end of the vessel 807, and a dip pipe 1190 extendsdown the center of the vessel 807 from the exhaust outlet 820 part wayto the bottom of the vessel. In this way, the gases flow in the oppositevertical direction than in the separator 806, and the tubular vessel 807is obstructed by the dip pipe 1190 rather than being substantiallyunobstructed. The dip pipe 1190 forms a conduit between the fan 852 andan open bottom end 1192 of the dip pipe. The open bottom end 1192 islocated above the normal liquid level 828 held in the liquid/solidcollection zone, such as the sump 808, at the bottom of the vessel 807.In this arrangement, droplet-laden gas enters the vessel 807tangentially at the top, and the dip pipe 1190 conducts the gas firstdownwardly through the vessel 807 around the dip pipe 1190 to the openbottom end 1192 of the dip pipe, and then upwardly through the dip pipe1190 to the fan 852, which is preferably located within the dip pipe,and subsequently out the exhaust outlet 820. In this design, the liquidconcentrator 1100 in some arrangements can be more compact, i.e.,shorter and/or smaller diameter, than the liquid concentrator 800, 900,or 1000 for a given efficiency as the downward motion of the gas pushesliquid that impinges on the wall downward into the collection sumprather than pushing against the force of gravity when the gas flowsupward over the liquid film, as in the separator 106. The liquidconcentrator may include any sump, settling chambers, and/orrecirculation system as previously described herein, or that mayotherwise be effective for performing such functions. For example, thebottom of the vessel 807 in the sump area 808 can function as a settlingtank that has a larger diameter than the body of the vessel 807 and maybe equipped with a cone bottom.

While the liquid concentrators 800, 900, 1000, and 1100 have beendisclosed primarily as using venturi evaporators, the evaporatorsections are not limited necessarily to using a venturi to evaporateliquids out of the wastewater. Rather the evaporator section may includeadditional and/or alternative mechanisms for promoting evaporation ofthe liquids out of the wastewater, such as with direct flame injectionports, heat transfer panels, draft tubes, static mixers, etc. In factalthough the mixing corridor is generally described with a continuousgas phase being merged with a discontinuous liquid phase, i.e. dropletsof water being injected into a large stream of gases, the mixingcorridor and evaporator section may alternatively include adiscontinuous gas phase merged with a continuous liquid phase, i.e.injection of gas bubbles into a large volume of liquid such as with adraft tube assembly. Thus, many of the features disclosed in the liquidconcentrators 800, 900, 1000, and 1100 are not necessarily dependentupon the particular type of evaporator or evaporative machinery.

While certain representative embodiments and details have been shown forpurposes of illustrating the invention, it will be apparent to thoseskilled in the art that various changes in the methods and apparatusdisclosed herein may be made without departing from the scope of theinvention.

1-12. (canceled)
 13. A liquid concentrator comprising: an evaporatorassembly defining a mixing corridor having a mixing chamber arranged toreceive wastewater and gas and an evaporator section connected with themixing chamber arranged to mix the wastewater with the gas and evaporateliquids from the wastewater; a cyclonic separator operatively connectedwith the evaporator section and arranged to receive the mixed wastewaterand gas and to separate the gas and the evaporated liquids from solidsand the wastewater; and a conduit arranged to transfer the wastewaterseparated in the cyclonic separator to a liquid inlet opening into themixing chamber, wherein the liquid inlet comprises a low-pressureinjection port, wherein the low-pressure injection port injectswastewater at a pressure of about ten psig or less.
 14. The liquidconcentrator of claim 13, wherein the low-pressure injection portinjects the wastewater at a pressure of about five psig or less.
 15. Theliquid concentrator of claim 14, wherein the low-pressure injection portinjects the wastewater at a pressure of about two psig.
 16. The liquidconcentrator of claim 13, wherein the low-pressure injection portincludes a spray nozzle.
 17. The liquid concentrator of claim 13,wherein the low-pressure injection port does not have a spray nozzle.18. The liquid concentrator of claim 17, comprising a baffle arranged todeflect wastewater entering the mixing chamber through the low-pressureinjection port.
 19. A liquid concentrator comprising: an evaporatorassembly arranged to mix wastewater with gas and evaporate liquids fromthe wastewater a cyclonic separator arranged to receive the mixedwastewater and gas from the evaporator assembly and to separate the gasand the evaporated liquids from solids and the wastewater; and a doorcovering an opening into the cyclonic separator, the door attached tothe cyclonic separator with a hinge, and a latch for latching the doorin a closed position covering the opening.
 20. The liquid concentratorof claim 19, wherein the latch comprises a quick-release latch.
 21. Theliquid concentrator of claim 19, comprising a seal arranged to form aseal between the door and the cyclonic separator.
 22. The liquidconcentrator of claim 19, wherein the opening is sized to receive aperson therethrough.
 23. A liquid concentrator comprising: an evaporatorassembly arranged to mix wastewater with gas and evaporate liquids fromthe wastewater; and a cyclonic separator arranged to receive the mixedwastewater and gas from the evaporator assembly through an inletadjacent a top end of the cyclonic separator, an exhaust outlet at thetop end of the cyclonic separator, and a pipe on the inside of thecyclonic separator extending from the exhaust outlet to an open bottomend located below the inlet, wherein the mixed wastewater and gastravels downwardly from the inlet to the open bottom end of the pipe andthen up an inside of the pipe to the exhaust outlet, whereby the gas andthe evaporated liquids are separated from solids and the wastewater, 24.The liquid concentrator of claim 23, further comprising a fan arrangedto draw the gases from the inlet through the cyclonic separator and thepipe.
 25. The liquid concentrator of claim 24, wherein the fan isdisposed inside the pipe.
 26. The liquid concentrator of claim 25,wherein the pipe is oriented vertically and aligned with an axis of thecyclonic separator.
 27. The liquid concentrator of claim 23, wherein thecyclonic separator comprise a tubular vessel and a sump at a bottom endof the tubular vessel, the sump having a cone-shaped bottom.
 28. Theliquid concentrator of claim 27, further comprising a liquid transferconduit that transfers wastewater from the sump to the evaporatorassembly.
 29. The liquid concentrator of claim 28, wherein the sump hasa larger diameter than the tubular vessel.